Add another LSan suppression for browser tests.

BUG=none
TBR=glider@chromium.org

Review URL: https://codereview.chromium.org/37533002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230457 0039d316-1c4b-4281-b951-d872f2087c98
Only throttle input to the render widget for heavy input handlers

This tracks the total time spent handling input on the main thread
for the current frame and only throttles input events once the
total time has reached a threshold.

If a cheap and reliable HighResNow is not available, the handlers
are assumed to be heavy.

TEST=Manually run MapsGL in a small window so it hits 60fps. Verified
panning tracks pointer more closely when using a 120Hz mouse.

Also tested with http://thj.no/personal/latency_test_case.html. This
patch produces visibly lower latency and allows the app to receive
more mouse move events to produce smoother curves.

BUG=305210

Review URL: https://codereview.chromium.org/25687004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230458 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 230458