Remove obsolete SynthesizeScrollGesture method.
Tidy up after the interface change to Input.synthesizeScrollGesture
Patch 4 of 4 to fix the overly long delay between
each scroll in smoothness.scrolling_tough_ad_cases caused by the render
thread being unresponsive.
Patch 1: https://codereview.chromium.org/
1299643004/
Patch 2: https://codereview.chromium.org/
1296993002/
Patch 3: https://codereview.chromium.org/
1291513004/
BUG=510398
Review URL: https://codereview.chromium.org/
1285133008
Cr-Commit-Position: refs/heads/master@{#346624}