Started on this build:

https://build.chromium.org/p/chromium.memory.fyi/builders/Windows%20Content%20Browser%20%28DrMemory%29/builds/6897

looks like these two CLs are culprit:

https://codereview.chromium.org/1809553002 (blink: Remove unused or rarely used methods from WebGraphicsContext3D)
https://codereview.chromium.org/1807813002 (Remove WebGraphicsContext3D dependency in gpu_context_tests.h)

danakj@, since this is ANADDRESSABLE ACCESS, I'll revert them unless I hear from you soon. (I'll ping you)
Let me know if you're already working on a fix, or you think your CL is unrelated.

log:
https://build.chromium.org/p/chromium.memory.fyi/builders/Windows%20Content%20Browser%20%28DrMemory%29/builds/6897/steps/memory%20test%3A%20content_browsertests/logs/stdio

UNADDRESSABLE ACCESS: reading 0x00000000-0x00000004 4 byte(s)
# 0 `anonymous namespace'::SignalTest_InvalidSignalSyncTokenTest_Test::RunTestOnMainThread [content\common\gpu\client\gpu_context_tests.h:67]
# 1 content::ContentBrowserTest::RunTestOnMainThreadLoop                       [content\public\test\content_browser_test.cc:134]
# 2 content::BrowserTestBase::ProxyRunTestOnMainThreadLoop                     [content\public\test\browser_test_base.cc:309]
# 3 content::ShellBrowserMainParts::PreMainMessageLoopRun                      [content\shell\browser\shell_browser_main_parts.cc:171]
# 4 content.dll!content::BrowserMainLoop::PreMainMessageLoopRun                [content\browser\browser_main_loop.cc:942]
# 5 content.dll!base::internal::Invoker<>::Run                                 [base\bind_internal.h:352]
# 6 content.dll!content::StartupTaskRunner::RunAllTasksNow                     [content\browser\startup_task_runner.cc:45]
# 7 content.dll!content::BrowserMainLoop::CreateStartupTasks                   [content\browser\browser_main_loop.cc:817]
# 8 content.dll!content::BrowserMainRunnerImpl::Initialize                     [content\browser\browser_main_runner.cc:137]
# 9 ShellBrowserMain                                                           [content\shell\browser\shell_browser_main.cc:23]
#10 content::ShellMainDelegate::RunProcess                                     [content\shell\app\shell_main_delegate.cc:275]
#11 content.dll!content::RunNamedProcessTypeMain                               [content\app\content_main_runner.cc:386]
#12 content.dll!content::ContentMainRunnerImpl::Run                            [content\app\content_main_runner.cc:772]
#13 content.dll!content::ContentMain                                           [content\app\content_main.cc:19]
#14 content::BrowserTestBase::SetUp                                            [content\public\test\browser_test_base.cc:282]
#15 content::ContentBrowserTest::SetUp                                         [content\public\test\content_browser_test.cc:92]
#16 testing::internal::HandleExceptionsInMethodIfSupported<>                   [testing\gtest\src\gtest.cc:2458]
Note: @0:00:18.305 in thread 1900
Note: instruction: mov    (%eax) -> %esi
The report came from the `SignalTest.InvalidSignalSyncTokenTest` test.
Suppression (error hash=#025835F7B91A8833#):
For more info on using suppressions see http://dev.chromium.org/developers/how-tos/using-drmemory#TOC-Suppressing-error-reports-from-the-
{
UNADDRESSABLE ACCESS
name=<insert_a_suppression_name_here>
*!`anonymous namespace'::SignalTest_InvalidSignalSyncTokenTest_Test::RunTestOnMainThread
*!content::ContentBrowserTest::RunTestOnMainThreadLoop
*!content::BrowserTestBase::ProxyRunTestOnMainThreadLoop
*!content::ShellBrowserMainParts::PreMainMessageLoopRun
content.dll!content::BrowserMainLoop::PreMainMessageLoopRun
content.dll!base::internal::Invoker<>::Run
content.dll!content::StartupTaskRunner::RunAllTasksNow
content.dll!content::BrowserMainLoop::CreateStartupTasks
content.dll!content::BrowserMainRunnerImpl::Initialize
*!ShellBrowserMain
*!content::ShellMainDelegate::RunProcess
content.dll!content::RunNamedProcessTypeMain
content.dll!content::ContentMainRunnerImpl::Run
content.dll!content::ContentMain
*!content::BrowserTestBase::SetUp
*!content::ContentBrowserTest::SetUp
*!testing::internal::HandleExceptionsInMethodIfSupported<>
}