Fix mouse moves on about:gpu timeline
Fix mouse moves on about:gpu timeline

R=jbates@chromium.org
BUG=84213
TBR=arv@chromium.org

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@87050 0039d316-1c4b-4281-b951-d872f2087c98

adobe/chromium,adobe/chromium,adobe/chromium,adobe/chromium,gavinp/chromium,adobe/chromium,gavinp/chromium,yitian134/chromium,ropik/chromium,ropik/chromium,ropik/chromium,yitian134/chromium,adobe/chromium,yitian134/chromium,ropik/chromium,gavinp/chromium,yitian134/chromium,gavinp/chromium,ropik/chromium,gavinp/chromium,yitian134/chromium,adobe/chromium,gavinp/chromium,gavinp/chromium,yitian134/chromium,ropik/chromium,gavinp/chromium,ropik/chromium,adobe/chromium,adobe/chromium,gavinp/chromium,adobe/chromium,yitian134/chromium,gavinp/chromium,adobe/chromium,yitian134/chromium,ropik/chromium,ropik/chromium,yitian134/chromium,yitian134/chromium