Looks like they are crashing:

	0   CoreFoundation                      0x00007fff79b6457b __exceptionPreprocess + 171
	1   unit_tests                          0x0000000108f79f87 _ZN6chromeL25ObjcExceptionPreprocessorEP11objc_object + 1271
	2   libobjc.A.dylib                     0x00007fff8edbd1da objc_exception_throw + 48
	3   CoreFoundation                      0x00007fff79be1c55 +[NSException raise:format:] + 197
	4   unit_tests                          0x0000000105f1dfa4 -[OCMBoxedReturnValueProvider handleInvocation:] + 468
	5   CoreFoundation                      0x00007fff79adeb83 -[NSArray makeObjectsPerformSelector:withObject:] + 275
	6   unit_tests                          0x0000000105f20630 -[OCMInvocationStub handleInvocation:] + 80
	7   unit_tests                          0x0000000105f24649 -[OCMockObject handleInvocation:] + 1081
	8   unit_tests                          0x0000000105f2413c -[OCMockObject forwardInvocation:] + 44
	9   CoreFoundation                      0x00007fff79ad7a88 ___forwarding___ + 536
	10  CoreFoundation                      0x00007fff79ad77e8 _CF_forwarding_prep_0 + 120
	11  unit_tests                          0x000000010ddce21b -[BookmarkBarFolderView performDragOperationForBookmarkButton:] + 219
	12  unit_tests                          0x000000010ddce41a -[BookmarkBarFolderView performDragOperation:] + 170
	13  unit_tests                          0x00000001056c788a _ZN12_GLOBAL__N_170BookmarkBarFolderViewTest_BookmarkButtonDragAndDropAcrossProfiles_Test8TestBodyEv + 1306
	14  unit_tests                          0x0000000105f9967e _ZN7testing8internal38HandleSehExceptionsInMethodIfSupportedINS_4TestEvEET0_PT_MS4_FS3_vEPKc + 126
	15  unit_tests                          0x0000000105f74da2 _ZN7testing8internal35HandleExceptionsInMethodIfSupportedINS_4TestEvEET0_PT_MS4_FS3_vEPKc + 114
	16  unit_tests                          0x0000000105f74cd6 _ZN7testing4Test3RunEv + 198
	17  unit_tests                          0x0000000105f75e1d _ZN7testing8TestInfo3RunEv + 221
	18  unit_tests                          0x0000000105f7717c _ZN7testing8TestCase3RunEv + 236
	19  unit_tests                          0x0000000105f8471a _ZN7testing8internal12UnitTestImpl11RunAllTestsEv + 922
	20  unit_tests                          0x0000000105f9cabe _ZN7testing8internal38HandleSehExceptionsInMethodIfSupportedINS0_12UnitTestImplEbEET0_PT_MS4_FS3_vEPKc + 126
	21  unit_tests                          0x0000000105f84302 _ZN7testing8internal35HandleExceptionsInMethodIfSupportedINS0_12UnitTestImplEbEET0_PT_MS4_FS3_vEPKc + 114
	22  unit_tests                          0x0000000105f841e2 _ZN7testing8UnitTest3RunEv + 370
	23  unit_tests                          0x0000000107d8d301 _Z13RUN_ALL_TESTSv + 17
	24  unit_tests                          0x0000000107d8c691 _ZN4base9TestSuite3RunEv + 337
	25  unit_tests                          0x00000001080e84dd _ZN7content17UnitTestTestSuite3RunEv + 45
	26  unit_tests                          0x0000000107d5a66d _ZN4base8internal13FunctorTraitsIMN7content17UnitTestTestSuiteEFivEvE6InvokeIPS3_JEEEiS5_OT_DpOT0_ + 125
	27  unit_tests                          0x0000000107d5a5b4 _ZN4base8internal12InvokeHelperILb0EiE8MakeItSoIRKMN7content17UnitTestTestSuiteEFivEJPS5_EEEiOT_DpOT0_ + 68
	28  unit_tests                          0x0000000107d5a543 _ZN4base8internal7InvokerINS0_9BindStateIMN7content17UnitTestTestSuiteEFivEJNS0_17UnretainedWrapperIS4_EEEEEFivEE7RunImplIRKS6_RKNSt3__15tupleIJS8_EEEJLm0EEEEiOT_OT0_NSF_16integer_sequenceImJXspT1_EEEE + 99
	29  unit_tests                          0x0000000107d5a47c _ZN4base8internal7InvokerINS0_9BindStateIMN7content17UnitTestTestSuiteEFivEJNS0_17UnretainedWrapperIS4_EEEEEFivEE3RunEPNS0_13BindStateBaseE + 44
	30  unit_tests                          0x0000000108f6d4cd _ZNKR4base8CallbackIFivELNS_8internal8CopyModeE1ELNS2_10RepeatModeE1EE3RunEv + 61
	31  unit_tests                          0x0000000107dcb048 _ZN4base12_GLOBAL__N_123LaunchUnitTestsInternalERKNS_8CallbackIFivELNS_8internal8CopyModeE1ELNS3_10RepeatModeE1EEEmibRKNS1_IFvvELS4_1ELS5_1EEE + 376
	32  unit_tests                          0x0000000107dcae93 _ZN4base15LaunchUnitTestsEiPPcRKNS_8CallbackIFivELNS_8internal8CopyModeE1ELNS4_10RepeatModeE1EEE + 163
	33  unit_tests                          0x0000000107d5a255 main + 373
	34  libdyld.dylib                       0x00007fff8f69e235 start + 1

I can confirm I came to the same conclusion:
Last green: 
https://build.chromium.org/p/chromium.mac/builders/Mac10.12%20Tests/builds/4035
revision: 24d26d96043e73f01c63b8965370657556eb52a0 

First red:
https://build.chromium.org/p/chromium.mac/builders/Mac10.12%20Tests/builds/4038
revision: b674a6d9e1c8d0bb906163223eea585bdbab74c5

Gives blamelist: https://chromium.googlesource.com/chromium/src/+log/24d26d96043e73f01c63b8965370657556eb52a0..b674a6d9e1c8d0bb906163223eea585bdbab74c5?pretty=fuller

The blamelist doesn't give any clues, so I'm assigning to rsesek@chromium.org due to the most recent changes in https://cs.chromium.org/chromium/src/chrome/browser/ui/cocoa/bookmarks/bookmark_bar_folder_view_unittest.mm
I'll disable the tests for now.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/8b9b1c33fe14cbe901f6547d11c516c820268889

commit 8b9b1c33fe14cbe901f6547d11c516c820268889
Author: Henrik Kjellander <kjellander@chromium.org>
Date: Sun Aug 20 16:35:17 2017

Disable BookmarkBarFolderViewTest.BookmarkButtonDragAndDrop{,AcrossProfiles} test

The test is failing on Mac10.12 Tests since
https://build.chromium.org/p/chromium.mac/builders/Mac10.12%20Tests/builds/4038

BUG= 757063 
TBR=rsesek@chromium.org

Change-Id: Ib5afa8d0e25a77be00f8bbfab41c1369574abf43
Reviewed-on: https://chromium-review.googlesource.com/622788
Reviewed-by: Henrik Kjellander <kjellander@chromium.org>
Commit-Queue: Henrik Kjellander <kjellander@chromium.org>
Cr-Commit-Position: refs/heads/master@{#495842}
[modify] https://crrev.com/8b9b1c33fe14cbe901f6547d11c516c820268889/chrome/browser/ui/cocoa/bookmarks/bookmark_bar_folder_view_unittest.mm

kjellander: I don't know which recent change you're referring to. I last touched the file 6 years ago.

OK sorry for that, I didn't realize the change was 6 years old (code search blame layer doesn't show date).
Assigning to OWNER in https://cs.chromium.org/chromium/src/chrome/browser/ui/cocoa/bookmarks/OWNERS then, since me as sheriff was unable to find a culprit. The test likely needs more debugging.

I don't work on Mac bookmark code anymore.

If there are specific to browser_side_navigation_unit_tests, which is PlzNavigate I believe, re-assigning over to jam@ for triage.

Camille: can you take a look?

actually I just took a quick look. this was failing on plznavigate and non-plznavigate runs, and the test has since been disabled.

Thanks for looking. Updating title of the bug to not mention browser_side_navigation, then. I think this bug is for tracking fixing and re-enabling these tests.

Since we have a revision range:
https://chromium.googlesource.com/chromium/src/+log/24d26d96043e73f01c63b8965370657556eb52a0..b674a6d9e1c8d0bb906163223eea585bdbab74c5?pretty=fuller

Assigning to possible culprit from that range that changed Mac code:
https://chromium-review.googlesource.com/610501

Please take a look if it's your change to blame, or if not, please help find the right CL in the above range that's to blame. Thanks!

I know little about Mac and even less about mocking, but this appears to be a bug in the mocking on Mac; sdefresne@, maybe you can shed some light on this?

It's exceedingly unlikely that the test failure has anything to do with https://chromium-review.googlesource.com/610501, as that change merely tweaked the visual appearance of HTML INPUT TYPE=SEARCH fields.

The exception text from the crashing tests is (absurdly) long:

2017-08-18 09:38:56.995 unit_tests[6999:141436] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Return value cannot be used for method; method signature declares 

'^{BookmarkModel=^^?^^?{unique_ptr<bookmarks::BookmarkClient, std::__1::default_delete<bookmarks::BookmarkClient> >={__compressed_pair<bookmarks::BookmarkClient *, std::__1::default_delete<bookmarks::BookmarkClient> >=^{}}}B{BookmarkNode=^^?{basic_string<unsigned short, base::string16_internals::string16_char_traits, std::__1::allocator<unsigned short> >={__compressed_pair<std::__1::basic_string<unsigned short, base::string16_internals::string16_char_traits, std::__1::allocator<unsigned short> >::__rep, std::__1::allocator<unsigned short> >={__rep}}}^{}{vector<std::__1::unique_ptr<bookmarks::BookmarkNode, std::__1::default_delete<bookmarks::BookmarkNode> >, std::__1::allocator<std::__1::unique_ptr<bookmarks::BookmarkNode, std::__1::default_delete<bookmarks::BookmarkNode> > > >=^{}^{}{__compressed_pair<std::__1::unique_ptr<bookmarks::BookmarkNode, std::__1::default_delete<bookmarks::BookmarkNode> > *, std::__1::allocator<std::__1::unique_ptr<bookmarks::BookmarkNode, std::__1::default_delete<bookmarks::BookmarkNode> > > >=^{}}}^^?q{GURL={basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >={__compressed_pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::__rep, std::__1::allocator<char> >={__rep}}}B{Parsed={Component=ii}{Component=ii}{Component=ii}{Component=ii}{Component=ii}{Component=ii}{Component=ii}{Component=ii}B^{}}{unique_ptr<GURL, std::__1::default_delete<GURL> >={__compressed_pair<GURL *, std::__1::default_delete<GURL> >=^{}}}}i{Time=q}{Time=q}{Image={scoped_refptr<gfx::internal::ImageStorage>=^{}}}i{unique_ptr<GURL, std::__1::default_delete<GURL> >={__compressed_pair<GURL *, std::__1::default_delete<GURL> >=^{}}}iq{unique_ptr<std::__1::map<std::__1::basic_string<char>, std::__1::basic_string<char>, std::__1::less<std::__1::basic_string<char> >, std::__1::allocator<std::__1::pair<const std::__1::basic_string<char>, std::__1::basic_string<char> > > >, std::__1::default_delete<std::__1::map<std::__1::basic_string<char>, std::__1::basic_string<char>, std::__1::less<std::__1::basic_string<char> >, std::__1::allocator<std::__1::pair<const std::__1::basic_string<char>, std::__1::basic_string<char> > > > > >={__compressed_pair<std::__1::map<std::__1::basic_string<char>, std::__1::basic_string<char>, std::__1::less<std::__1::basic_string<char> >, std::__1::allocator<std::__1::pair<const std::__1::basic_string<char>, std::__1::basic_string<char> > > > *, std::__1::default_delete<std::__1::map<std::__1::basic_string<char>, std::__1::basic_string<char>, std::__1::less<std::__1::basic_string<char> >, std::__1::allocator<std::__1::pair<const std::__1::basic_string<char>, std::__1::basic_string<char> > > > > >=^{}}}q}^{}^{}^{}q{ObserverList<bookmarks::BookmarkModelObserver, false>={WeakReferenceOwner={scoped_refptr<base::internal::WeakReference::Flag>=^{}}}{vector<bookmarks::BookmarkModelObserver *, std::__1::allocator<bookmarks::BookmarkModelObserver *> >=^^{}^^{}{__compressed_pair<bookmarks::BookmarkModelObserver **, std::__1::allocator<bookmarks::BookmarkModelObserver *> >=^^{}}}ii}{multiset<bookmarks::BookmarkNode *, bookmarks::BookmarkModel::NodeURLComparator, std::__1::allocator<bookmarks::BookmarkNode *> >={__tree<bookmarks::BookmarkNode *, bookmarks::BookmarkModel::NodeURLComparator, std::__1::allocator<bookmarks::BookmarkNode *> >=^{}{__compressed_pair<std::__1::__tree_end_node<std::__1::__tree_node_base<void *> *>, std::__1::allocator<std::__1::__tree_node<bookmarks::BookmarkNode *, void *> > >={__tree_end_node<std::__1::__tree_node_base<void *> *>=^{}}}{__compressed_pair<unsigned long, bookmarks::BookmarkModel::NodeURLComparator>=Q}}}{Lock={LockImpl={_opaque_pthread_mutex_t=q[56c]}}}{CancelableTaskTracker={small_map<std::__1::map<long long, base::CancellationFlag *, std::__1::less<long long>, std::__1::allocator<std::__1::pair<const long long, base::CancellationFlag *> > >, 4, base::internal::select_equal_key<std::__1::map<long long, base::CancellationFlag *, std::__1::less<long long>, std::__1::allocator<std::__1::pair<const long long, base::CancellationFlag *> > >, false>::equal_key, base::internal::small_map_default_init<std::__1::map<long long, base::CancellationFlag *, std::__1::less<long long>, std::__1::allocator<std::__1::pair<const long long, base::CancellationFlag *> > > > >}q{SequenceChecker=}{WeakPtrFactory<base::CancelableTaskTracker>={WeakReferenceOwner={scoped_refptr<base::internal::WeakReference::Flag>=^{}}}Q}}{unique_ptr<bookmarks::BookmarkStorage, std::__1::default_delete<bookmarks::BookmarkStorage> >={__compressed_pair<bookmarks::BookmarkStorage *, std::__1::default_delete<bookmarks::BookmarkStorage> >=^{}}}{unique_ptr<bookmarks::TitledUrlIndex, std::__1::default_delete<bookmarks::TitledUrlIndex> >={__compressed_pair<bookmarks::TitledUrlIndex *, std::__1::default_delete<bookmarks::TitledUrlIndex> >=^{}}}{WaitableEvent=i{scoped_refptr<base::WaitableEvent::ReceiveRight>=^{}}{ScopedGeneric<unsigned int, base::mac::internal::SendRightTraits>={Data=I}}}i{unique_ptr<bookmarks::BookmarkExpandedStateTracker, std::__1::default_delete<bookmarks::BookmarkExpandedStateTracker> >={__compressed_pair<bookmarks::BookmarkExpandedStateTracker *, std::__1::default_delete<bookmarks::BookmarkExpandedStateTracker> >=^{}}}{set<std::__1::basic_string<char>, std::__1::less<std::__1::basic_string<char> >, std::__1::allocator<std::__1::basic_string<char> > >={__tree<std::__1::basic_string<char>, std::__1::less<std::__1::basic_string<char> >, std::__1::allocator<std::__1::basic_string<char> > >=^{}{__compressed_pair<std::__1::__tree_end_node<std::__1::__tree_node_base<void *> *>, std::__1::allocator<std::__1::__tree_node<std::__1::basic_string<char>, void *> > >={__tree_end_node<std::__1::__tree_node_base<void *> *>=^{}}}{__compressed_pair<unsigned long, std::__1::less<std::__1::basic_string<char> > >=Q}}}^{}{unique_ptr<bookmarks::BookmarkUndoDelegate, std::__1::default_delete<bookmarks::BookmarkUndoDelegate> >={__compressed_pair<bookmarks::BookmarkUndoDelegate *, std::__1::default_delete<bookmarks::BookmarkUndoDelegate> >=^{}}}}' 

but value is 

'^{BookmarkModel=^^?^^?{unique_ptr<bookmarks::BookmarkClient, std::__1::default_delete<bookmarks::BookmarkClient> >={__compressed_pair<bookmarks::BookmarkClient *, std::__1::default_delete<bookmarks::BookmarkClient> >=^{BookmarkClient}}}B{BookmarkNode=^^?{basic_string<unsigned short, base::string16_internals::string16_char_traits, std::__1::allocator<unsigned short> >={__compressed_pair<std::__1::basic_string<unsigned short, base::string16_internals::string16_char_traits, std::__1::allocator<unsigned short> >::__rep, std::__1::allocator<unsigned short> >={__rep=(?={__long=QQ^S}{__short=(?=CS)[11S]}{__raw=[3Q]})}}}^{BookmarkNode}{vector<std::__1::unique_ptr<bookmarks::BookmarkNode, std::__1::default_delete<bookmarks::BookmarkNode> >, std::__1::allocator<std::__1::unique_ptr<bookmarks::BookmarkNode, std::__1::default_delete<bookmarks::BookmarkNode> > > >=^{unique_ptr<bookmarks::BookmarkNode, std::__1::default_delete<bookmarks::BookmarkNode> >}^{unique_ptr<bookmarks::BookmarkNode, std::__1::default_delete<bookmarks::BookmarkNode> >}{__compressed_pair<std::__1::unique_ptr<bookmarks::BookmarkNode, std::__1::default_delete<bookmarks::BookmarkNode> > *, std::__1::allocator<std::__1::unique_ptr<bookmarks::BookmarkNode, std::__1::default_delete<bookmarks::BookmarkNode> > > >=^{unique_ptr<bookmarks::BookmarkNode, std::__1::default_delete<bookmarks::BookmarkNode> >}}}^^?q{GURL={basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >={__compressed_pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::__rep, std::__1::allocator<char> >={__rep=(?={__long=QQ*}{__short=(?=Cc)[23c]}{__raw=[3Q]})}}}B{Parsed={Component=ii}{Component=ii}{Component=ii}{Component=ii}{Component=ii}{Component=ii}{Component=ii}{Component=ii}B^{Parsed}}{unique_ptr<GURL, std::__1::default_delete<GURL> >={__compressed_pair<GURL *, std::__1::default_delete<GURL> >=^{GURL}}}}i{Time=q}{Time=q}{Image={scoped_refptr<gfx::internal::ImageStorage>=^{ImageStorage}}}i{unique_ptr<GURL, std::__1::default_delete<GURL> >={__compressed_pair<GURL *, std::__1::default_delete<GURL> >=^{GURL}}}iq{unique_ptr<std::__1::map<std::__1::basic_string<char>, std::__1::basic_string<char>, std::__1::less<std::__1::basic_string<char> >, std::__1::allocator<std::__1::pair<const std::__1::basic_string<char>, std::__1::basic_string<char> > > >, std::__1::default_delete<std::__1::map<std::__1::basic_string<char>, std::__1::basic_string<char>, std::__1::less<std::__1::basic_string<char> >, std::__1::allocator<std::__1::pair<const std::__1::basic_string<char>, std::__1::basic_string<char> > > > > >={__compressed_pair<std::__1::map<std::__1::basic_string<char>, std::__1::basic_string<char>, std::__1::less<std::__1::basic_string<char> >, std::__1::allocator<std::__1::pair<const std::__1::basic_string<char>, std::__1::basic_string<char> > > > *, std::__1::default_delete<std::__1::map<std::__1::basic_string<char>, std::__1::basic_string<char>, std::__1::less<std::__1::basic_string<char> >, std::__1::allocator<std::__1::pair<const std::__1::basic_string<char>, std::__1::basic_string<char> > > > > >=^{map<std::__1::basic_string<char>, std::__1::basic_string<char>, std::__1::less<std::__1::basic_string<char> >, std::__1::allocator<std::__1::pair<const std::__1::basic_string<char>, std::__1::basic_string<char> > > >}}}q}^{BookmarkPermanentNode}^{BookmarkPermanentNode}^{BookmarkPermanentNode}q{ObserverList<bookmarks::BookmarkModelObserver, false>={WeakReferenceOwner={scoped_refptr<base::internal::WeakReference::Flag>=^{Flag}}}{vector<bookmarks::BookmarkModelObserver *, std::__1::allocator<bookmarks::BookmarkModelObserver *> >=^^{BookmarkModelObserver}^^{BookmarkModelObserver}{__compressed_pair<bookmarks::BookmarkModelObserver **, std::__1::allocator<bookmarks::BookmarkModelObserver *> >=^^{BookmarkModelObserver}}}ii}{multiset<bookmarks::BookmarkNode *, bookmarks::BookmarkModel::NodeURLComparator, std::__1::allocator<bookmarks::BookmarkNode *> >={__tree<bookmarks::BookmarkNode *, bookmarks::BookmarkModel::NodeURLComparator, std::__1::allocator<bookmarks::BookmarkNode *> >=^{__tree_end_node<std::__1::__tree_node_base<void *> *>}{__compressed_pair<std::__1::__tree_end_node<std::__1::__tree_node_base<void *> *>, std::__1::allocator<std::__1::__tree_node<bookmarks::BookmarkNode *, void *> > >={__tree_end_node<std::__1::__tree_node_base<void *> *>=^{__tree_node_base<void *>}}}{__compressed_pair<unsigned long, bookmarks::BookmarkModel::NodeURLComparator>=Q}}}{Lock={LockImpl={_opaque_pthread_mutex_t=q[56c]}}}{CancelableTaskTracker={small_map<std::__1::map<long long, base::CancellationFlag *, std::__1::less<long long>, std::__1::allocator<std::__1::pair<const long long, base::CancellationFlag *> > >, 4, base::internal::select_equal_key<std::__1::map<long long, base::CancellationFlag *, std::__1::less<long long>, std::__1::allocator<std::__1::pair<const long long, base::CancellationFlag *> > >, false>::equal_key, base::internal::small_map_default_init<std::__1::map<long long, base::CancellationFlag *, std::__1::less<long long>, std::__1::allocator<std::__1::pair<const long long, base::CancellationFlag *> > > > >=i{small_map_default_init<std::__1::map<long long, base::CancellationFlag *, std::__1::less<long long>, std::__1::allocator<std::__1::pair<const long long, base::CancellationFlag *> > > >=}(?=[4{ManualConstructor<std::__1::pair<const long long, base::CancellationFlag *> >=[16c]}]{ManualConstructor<std::__1::map<long long, base::CancellationFlag *, std::__1::less<long long>, std::__1::allocator<std::__1::pair<const long long, base::CancellationFlag *> > > >=[24c]})}q{SequenceChecker=}{WeakPtrFactory<base::CancelableTaskTracker>={WeakReferenceOwner={scoped_refptr<base::internal::WeakReference::Flag>=^{Flag}}}Q}}{unique_ptr<bookmarks::BookmarkStorage, std::__1::default_delete<bookmarks::BookmarkStorage> >={__compressed_pair<bookmarks::BookmarkStorage *, std::__1::default_delete<bookmarks::BookmarkStorage> >=^{BookmarkStorage}}}{unique_ptr<bookmarks::TitledUrlIndex, std::__1::default_delete<bookmarks::TitledUrlIndex> >={__compressed_pair<bookmarks::TitledUrlIndex *, std::__1::default_delete<bookmarks::TitledUrlIndex> >=^{TitledUrlIndex}}}{WaitableEvent=i{scoped_refptr<base::WaitableEvent::ReceiveRight>=^{ReceiveRight}}{ScopedGeneric<unsigned int, base::mac::internal::SendRightTraits>={Data=I}}}i{unique_ptr<bookmarks::BookmarkExpandedStateTracker, std::__1::default_delete<bookmarks::BookmarkExpandedStateTracker> >={__compressed_pair<bookmarks::BookmarkExpandedStateTracker *, std::__1::default_delete<bookmarks::BookmarkExpandedStateTracker> >=^{BookmarkExpandedStateTracker}}}{set<std::__1::basic_string<char>, std::__1::less<std::__1::basic_string<char> >, std::__1::allocator<std::__1::basic_string<char> > >={__tree<std::__1::basic_string<char>, std::__1::less<std::__1::basic_string<char> >, std::__1::allocator<std::__1::basic_string<char> > >=^{__tree_end_node<std::__1::__tree_node_base<void *> *>}{__compressed_pair<std::__1::__tree_end_node<std::__1::__tree_node_base<void *> *>, std::__1::allocator<std::__1::__tree_node<std::__1::basic_string<char>, void *> > >={__tree_end_node<std::__1::__tree_node_base<void *> *>=^{__tree_node_base<void *>}}}{__compressed_pair<unsigned long, std::__1::less<std::__1::basic_string<char> > >=Q}}}^{BookmarkUndoDelegate}{unique_ptr<bookmarks::BookmarkUndoDelegate, std::__1::default_delete<bookmarks::BookmarkUndoDelegate> >={__compressed_pair<bookmarks::BookmarkUndoDelegate *, std::__1::default_delete<bookmarks::BookmarkUndoDelegate> >=^{BookmarkUndoDelegate}}}}'.'

A similar problem is seen in Issue 736987, which is summarized as "The issue is that those two types are considered as incompatible by OCMock while the developer thought they were (and they probably were)... The code in third_party/ocmock/OCMock/OCMFunctions.m is supposed to parse those and accept those differences."

Nothing in the regression range shown in #9 seems likely to have impacted this. The last CL /before/ the regression range (24d26d96043e73f01c63b8965370657556eb52a0) is "base::less -> std::less<> from C++14." which seems like it could be relevant.

Removing sheriff label because the failing tests have been disabled.

This is most likely caused by a change from base::less to std::less.