Suppress reports on benign race on vfptr in ChromeThread.
Suppress reports on benign race on vfptr in ChromeThread.

This has started showing up on TSan/Linux/unit like this:
WARNING: Possible data race during write of size 4 at 0xAEF33E0: {{{
   T0 (locks held: {}):
    #0  ChromeThread::~ChromeThread() chrome/browser/chrome_thread.cc:44
    #1  ImageLoadingTrackerTest::~ImageLoadingTrackerTest() chrome/browser/extensions/image_loading_tracker_unittest.cc:17
    #2  ImageLoadingTrackerTest_Cache_Test::~ImageLoadingTrackerTest_Cache_Test() chrome/browser/extensions/image_loading_tracker_unittest.cc:95
    #3  testing::internal::TestInfoImpl::Run() testing/gtest/src/gtest.cc:2319
  Concurrent read(s) happened at (OR AFTER) these points:
   T462 (Chrome_IOThread) (locks held: {}):
    #0  base::Thread::ThreadMain() base/thread.cc:156
    #1  ThreadFunc(void*) base/platform_thread_posix.cc:26
    #2  ThreadSanitizerStartThread ts_valgrind_intercepts.c:571
}}}

http://build.chromium.org/buildbot/memory/builders/Linux%20Tests%20(tsan)/builds/3340

TBR=glider
BUG=25385
Review URL: http://codereview.chromium.org/1572008

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@43189 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser