As you can see from:

https://chromium-review.googlesource.com/c/442284/

...and the associated bug, crash reports were busted for a while in a pretty major way.  

That was fixed.  You can see the M57 pick landed Feb 16 at:

  https://chromium-review.googlesource.com/c/443308

...but we are still seeing a certain class of crashes that has no good crash reports.  Specifically see:

a767e034a0000000

When I look at that report I still see a stack quality of 18% and I see "Missing symbols: chrome".  The crash is from 9202.51.0 on 2017-03-08 

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...but if I download this type of crash and symbolize manually and go into GDB then I get a wonderfully nice stack crawl.

(gdb) bt
#0  0xece0fb36 in ?? () from r/lib/libc.so.6
#1  0xece1ecd4 in raise () from r/lib/libc.so.6
#2  0xece1fc36 in abort () from r/lib/libc.so.6
#3  0xb771808e in base::debug::BreakDebugger() () at ../../../../../../../home/chrome-bot/chrome_root/src/base/debug/debugger_posix.cc:251
#4  0xb77248b2 in logging::LogMessage::~LogMessage() () at ../../../../../../../home/chrome-bot/chrome_root/src/base/logging.cc:759
#5  0xb7739630 in base::(anonymous namespace)::OnNoMemorySize(unsigned int) [clone .constprop.4] () at ../../../../../../../home/chrome-bot/chrome_root/src/base/process/memory_linux.cc:35
#6  0xb6296c82 in operator new(unsigned int, std::nothrow_t const&) () at ../../../../../../../home/chrome-bot/chrome_root/src/base/allocator/allocator_shim.cc:68
#7  0xb82b2476 in leveldb::ReadBlock(leveldb::RandomAccessFile*, leveldb::ReadOptions const&, leveldb::BlockHandle const&, leveldb::BlockContents*) ()
    at ../../../../../../../home/chrome-bot/chrome_root/src/third_party/leveldatabase/src/table/format.cc:124
#8  0xb82ad92a in leveldb::Table::BlockReader(void*, leveldb::ReadOptions const&, leveldb::Slice const&) ()
    at ../../../../../../../home/chrome-bot/chrome_root/src/third_party/leveldatabase/src/table/table.cc:189
#9  0xb82aecee in leveldb::(anonymous namespace)::TwoLevelIterator::InitDataBlock() () at ../../../../../../../home/chrome-bot/chrome_root/src/third_party/leveldatabase/src/table/two_level_iterator.cc:165
#10 0xb82aeef4 in leveldb::(anonymous namespace)::TwoLevelIterator::Seek(leveldb::Slice const&) ()
    at ../../../../../../../home/chrome-bot/chrome_root/src/third_party/leveldatabase/src/table/two_level_iterator.cc:93
#11 0xb82ad422 in leveldb::IteratorWrapper::Seek(leveldb::Slice const&) () at ../../../../../../../home/chrome-bot/chrome_root/src/third_party/leveldatabase/src/table/iterator_wrapper.h:47
#12 0xb82ad460 in leveldb::(anonymous namespace)::MergingIterator::Seek(leveldb::Slice const&) () at ../../../../../../../home/chrome-bot/chrome_root/src/third_party/leveldatabase/src/table/merger.cc:53
#13 0xb82a1ea0 in leveldb::(anonymous namespace)::DBIter::Seek(leveldb::Slice const&) () at ../../../../../../../home/chrome-bot/chrome_root/src/third_party/leveldatabase/src/db/db_iter.cc:280
#14 0xb6e2f934 in content::LevelDBIteratorImpl::Seek(base::BasicStringPiece<std::string> const&) ()
    at ../../../../../../../home/chrome-bot/chrome_root/src/content/browser/indexed_db/leveldb/leveldb_iterator_impl.cc:45
#15 0xb6e303ca in content::LevelDBTransaction::TransactionIterator::Seek(base::BasicStringPiece<std::string> const&) ()
    at ../../../../../../../home/chrome-bot/chrome_root/src/content/browser/indexed_db/leveldb/leveldb_transaction.cc:230
#16 0xb6e056c0 in content::IndexedDBBackingStore::Cursor::FirstSeek(leveldb::Status*) () at ../../../../../../../home/chrome-bot/chrome_root/src/content/browser/indexed_db/indexed_db_backing_store.cc:3182
#17 0xb6e09778 in content::IndexedDBBackingStore::OpenObjectStoreCursor(content::IndexedDBBackingStore::Transaction*, long long, long long, content::IndexedDBKeyRange const&, blink::WebIDBCursorDirection, leveldb::Status*) () at ../../../../../../../home/chrome-bot/chrome_root/src/content/browser/indexed_db/indexed_db_backing_store.cc:3969
#18 0xb6e1a138 in content::IndexedDBDatabase::OpenCursorOperation(std::unique_ptr<content::IndexedDBDatabase::OpenCursorOperationParams, std::default_delete<content::IndexedDBDatabase::OpenCursorOperationParams> >, content::IndexedDBTransaction*) () at ../../../../../../../home/chrome-bot/chrome_root/src/content/browser/indexed_db/indexed_db_database.cc:1536
#19 0xb6e1c5f8 in base::internal::Invoker<base::internal::BindState<leveldb::Status (content::IndexedDBDatabase::*)(std::unique_ptr<content::IndexedDBDatabase::OpenCursorOperationParams, std::default_delete<content::IndexedDBDatabase::OpenCursorOperationParams> >, content::IndexedDBTransaction*), scoped_refptr<content::IndexedDBDatabase>, base::internal::PassedWrapper<std::unique_ptr<content::IndexedDBDatabase::OpenCursorOperationParams, std::default_delete<content::IndexedDBDatabase::OpenCursorOperationParams> > > >, leveldb::Status (content::IndexedDBTransaction*)>::Run(base::internal::BindStateBase*, content::IndexedDBTransaction*&&) () at ../../../../../../../home/chrome-bot/chrome_root/src/base/bind_internal.h:214
#20 0xb6e2d200 in content::IndexedDBTransaction::ProcessTaskQueue() () at ../../../../../../../home/chrome-bot/chrome_root/src/base/callback.h:85
#21 0xb63fd84c in base::debug::TaskAnnotator::RunTask(char const*, base::PendingTask*) () at ../../../../../../../home/chrome-bot/chrome_root/src/base/callback.h:68
#22 0xb63f2212 in base::MessageLoop::DoWork() () at ../../../../../../../home/chrome-bot/chrome_root/src/base/message_loop/message_loop.cc:421
#23 0xb63f2608 in base::MessagePumpDefault::Run(base::MessagePump::Delegate*) () at ../../../../../../../home/chrome-bot/chrome_root/src/base/message_loop/message_pump_default.cc:33
#24 0xb773e02a in base::RunLoop::Run() () at ../../../../../../../home/chrome-bot/chrome_root/src/base/run_loop.cc:37
#25 0xb7750c30 in base::Thread::ThreadMain() () at ../../../../../../../home/chrome-bot/chrome_root/src/base/threading/thread.cc:328
#26 0xb774ed5e in base::(anonymous namespace)::ThreadFunc(void*) () at ../../../../../../../home/chrome-bot/chrome_root/src/base/threading/platform_thread_posix.cc:71
#27 0xed4385fa in ?? () from r/lib/libpthread.so.0


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What's wrong?