This looks like a problem with a specific navigation test

Failed again today: https://touch-swarming.appspot.com/task?id=36b54ed7f7c16a10&refresh=10&show_raw=1

I've sent out https://codereview.chromium.org/2937693002/ to disable this test on devices.

Looking at the swarming logs, it appears that this test only has issues on iOS 9.3.2 devices.  I see failures on both phone and tablet, but no failures on iOS10 or on simulator.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4fc8601f5e8bc4bcefed93f3edefbb70dc163fbd

commit 4fc8601f5e8bc4bcefed93f3edefbb70dc163fbd
Author: rohitrao <rohitrao@chromium.org>
Date: Tue Jun 13 12:50:30 2017

[ios] Disables WindowLocationTest.WindowLocationSetToDOMString on device.

This test occasionally times out on iOS 9.3.2 devices.

BUG=731740

Review-Url: https://codereview.chromium.org/2937693002
Cr-Commit-Position: refs/heads/master@{#478987}

[modify] https://crrev.com/4fc8601f5e8bc4bcefed93f3edefbb70dc163fbd/ios/web/navigation/window_location_inttest.mm

[ RUN      ] WindowLocationTest.WindowLocationSetToDOMString
(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
  * frame #0: 0x00000001812d0fd8 libsystem_kernel.dylib`mach_msg_trap + 8
    frame #1: 0x00000001812d0e54 libsystem_kernel.dylib`mach_msg + 72
    frame #2: 0x0000000181708c60 CoreFoundation`__CFRunLoopServiceMachPort + 196
    frame #3: 0x0000000181706964 CoreFoundation`__CFRunLoopRun + 1032
    frame #4: 0x0000000181630c50 CoreFoundation`CFRunLoopRunSpecific + 384
    frame #5: 0x0000000182040cfc Foundation`-[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 308
    frame #6: 0x0000000100540878 ios_web_inttests`base::test::ios::SpinRunLoopWithMaxDelay(max_delay=(delta_ = 10000)) at wait_util.mm:57
    frame #7: 0x0000000100540510 ios_web_inttests`base::test::ios::TimeUntilCondition(action=(null), condition=0x000000010014e12c, run_message_loop=false, timeout=(delta_ = 100000000000)) block_pointer, bool () block_pointer, bool, base::TimeDelta) at wait_util.mm:32
    frame #8: 0x00000001005408f8 ios_web_inttests`base::test::ios::WaitUntilCondition(condition=0x000000010014e12c, run_message_loop=false, timeout=(delta_ = 0)) block_pointer, bool, base::TimeDelta) at wait_util.mm:47
    frame #9: 0x0000000100540948 ios_web_inttests`base::test::ios::WaitUntilCondition(condition=0x000000010014e12c) block_pointer) at wait_util.mm:51
    frame #10: 0x000000010014dfc0 ios_web_inttests`web::WebIntTest::ExecuteBlockAndWaitForLoad(this=0x0000000137d5e460, url=0x000000016fd6c968, block=0x00000001001654f8) block_pointer) at web_int_test.mm:99
    frame #11: 0x0000000100165198 ios_web_inttests`WindowLocationTest_WindowLocationSetToDOMString_Test::TestBody(this=0x0000000137d5e460) at window_location_inttest.mm:241
    frame #12: 0x00000001004cc1dc ios_web_inttests`void testing::internal::HandleSehExceptionsInMethodIfSupported<testing::Test, void>(object=0x0000000137d5e460, method=20 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00, location="the test body")(), char const*) at gtest.cc:2399
    frame #13: 0x00000001004ad490 ios_web_inttests`void testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void>(object=0x0000000137d5e460, method=20 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00, location="the test body")(), char const*) at gtest.cc:2452
    frame #14: 0x00000001004ad3c4 ios_web_inttests`testing::Test::Run(this=0x0000000137d5e460) at gtest.cc:2471
    frame #15: 0x00000001004ae324 ios_web_inttests`testing::TestInfo::Run(this=0x0000000137d075d0) at gtest.cc:2653
    frame #16: 0x00000001004af420 ios_web_inttests`testing::TestCase::Run(this=0x0000000137d06e80) at gtest.cc:2771
    frame #17: 0x00000001004b9f6c ios_web_inttests`testing::internal::UnitTestImpl::RunAllTests(this=0x0000000137e08ca0) at gtest.cc:4648
    frame #18: 0x00000001004cf74c ios_web_inttests`bool testing::internal::HandleSehExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(object=0x0000000137e08ca0, method=a4 9c 4b 00 01 00 00 00 00 00 00 00 00 00 00 00, location="auxiliary test code (environments or event listeners)")(), char const*) at gtest.cc:2399
    frame #19: 0x00000001004b9c18 ios_web_inttests`bool testing::internal::HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(object=0x0000000137e08ca0, method=a4 9c 4b 00 01 00 00 00 00 00 00 00 00 00 00 00, location="auxiliary test code (environments or event listeners)")(), char const*) at gtest.cc:2452
    frame #20: 0x00000001004b9b14 ios_web_inttests`testing::UnitTest::Run(this=0x0000000101feca18) at gtest.cc:4256
    frame #21: 0x00000001005425e0 ios_web_inttests`RUN_ALL_TESTS() at gtest.h:2237
    frame #22: 0x0000000100541adc ios_web_inttests`base::TestSuite::Run(this=0x000000016fd6f9b0) at test_suite.cc:271
    frame #23: 0x00000001005456e0 ios_web_inttests`::-[ChromeUnitTestDelegate runTests](self=0x0000000137e27590, _cmd="runTests") at test_support_ios.mm:157
    frame #24: 0x000000018211a658 Foundation`__NSFireDelayedPerform + 428
    frame #25: 0x0000000181709794 CoreFoundation`__CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 28
    frame #26: 0x0000000181709438 CoreFoundation`__CFRunLoopDoTimer + 884
    frame #27: 0x0000000181706b4c CoreFoundation`__CFRunLoopRun + 1520
    frame #28: 0x0000000181630c50 CoreFoundation`CFRunLoopRunSpecific + 384
    frame #29: 0x0000000182f18088 GraphicsServices`GSEventRunModal + 180
    frame #30: 0x000000018691e088 UIKit`UIApplicationMain + 204
    frame #31: 0x0000000100545a90 ios_web_inttests`base::RunTestsFromIOSApp() at test_support_ios.mm:213
    frame #32: 0x00000001005419dc ios_web_inttests`base::TestSuite::Run(this=0x000000016fd6f9b0) at test_suite.cc:252
    frame #33: 0x000000010016a20c ios_web_inttests`int base::internal::FunctorTraits<int (base::TestSuite::*)(), void>::Invoke<web::WebTestSuite*>(method=c0 19 54 00 01 00 00 00 00 00 00 00 00 00 00 00, receiver_ptr=0x000000016fd6f4b0)(), web::WebTestSuite*&&) at bind_internal.h:214
    frame #34: 0x000000010016a140 ios_web_inttests`int base::internal::InvokeHelper<false, int>::MakeItSo<int (functor=0x0000000137d09468, args=0x000000016fd6f4b0)(), web::WebTestSuite*>(int (base::TestSuite::* const&&&)(), web::WebTestSuite*&&) at bind_internal.h:285
    frame #35: 0x000000010016a0dc ios_web_inttests`int base::internal::Invoker<base::internal::BindState<int (base::TestSuite::*)(), base::internal::UnretainedWrapper<web::WebTestSuite> >, int ()>::RunImpl<int (functor=0x0000000137d09468, bound=0x0000000137d09478, (null)=IndexSequence<0> @ 0x000000016fd6f4c8)(), std::__1::tuple<base::internal::UnretainedWrapper<web::WebTestSuite> > const&, 0ul>(int (base::TestSuite::* const&&&)(), std::__1::tuple<base::internal::UnretainedWrapper<web::WebTestSuite> > const&&&, base::IndexSequence<0ul>) at bind_internal.h:361
    frame #36: 0x0000000100169fe0 ios_web_inttests`base::internal::Invoker<base::internal::BindState<int (base::TestSuite::*)(), base::internal::UnretainedWrapper<web::WebTestSuite> >, int ()>::Run(base=0x0000000137d09440) at bind_internal.h:339
    frame #37: 0x0000000100547b90 ios_web_inttests`base::Callback<int (), (base::internal::CopyMode)1, (base::internal::RepeatMode)1>::Run(this=0x000000016fd6f998) const at callback.h:80
    frame #38: 0x0000000100547b10 ios_web_inttests`base::LaunchUnitTests(argc=3, argv=0x000000016fd6fa58, run_test_suite=0x000000016fd6f998), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&) at unit_test_launcher_ios.cc:39
    frame #39: 0x0000000100169da0 ios_web_inttests`main(argc=3, argv=0x000000016fd6fa58) at run_all_unittests.cc:15
    frame #40: 0x00000001811ce8b8 libdyld.dylib`start + 4

Looks like we spin forever waiting for the following code to finish a page load:

  ExecuteBlockAndWaitForLoad(sample_url, ^{
    ASSERT_TRUE(web::test::TapWebViewElementWithId(
        web_state(), kWindowLocationSetToDOMStringID));
  });