Merge 67787 - Null-check of OnMsgDidActivateAcceleratedCompositing to avoid crash during tab closing.

BUG=64849
TEST=none

Review URL: http://codereview.chromium.org/5372009

TBR=nduca@chromium.org
Review URL: http://codereview.chromium.org/5480001

git-svn-id: svn://svn.chromium.org/chrome/branches/597/src@67875 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed