Android: Enable vsync for synthetic gestures

A recent refactoring accidentally removed the code that turns on vsync
for synthetic gestures. This causes the gesture to never start if
nothing else happens to turn on vsync at the same time.

BUG=370967
TEST=tools/perf/run_benchmark rasterize_and_record_micro.key_silk_cases
--browser=android-chrome --page-filter=slide_drawer

Review URL: https://codereview.chromium.org/269343013

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@269561 0039d316-1c4b-4281-b951-d872f2087c98

content/browser/renderer_host/render_widget_host_view_android.cc

@@ -1166,6 +1166,7 @@ void RenderWidgetHostViewAndroid::OnSetNeedsFlushInput() {
     return;
   TRACE_EVENT0("input", "RenderWidgetHostViewAndroid::OnSetNeedsFlushInput");
   flush_input_requested_ = true;
+  content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
 }
 
 void RenderWidgetHostViewAndroid::CreateBrowserAccessibilityManagerIfNeeded() {