Expand UMA coverage for compositor-handled events and fling FPS

content/child/blink_platform_impl.cc

Index: content/child/blink_platform_impl.cc
diff --git a/content/child/blink_platform_impl.cc b/content/child/blink_platform_impl.cc
index 022f29721f3b52e55f1a52a555cd2b949d5223f9..34964ebc085f4cba002de669a6b4f12c7c9457ee 100644
--- a/content/child/blink_platform_impl.cc
+++ b/content/child/blink_platform_impl.cc
@@ -1023,10 +1023,13 @@ blink::WebGestureCurve* BlinkPlatformImpl::createFlingAnimationCurve(
     blink::WebGestureDevice device_source,
     const blink::WebFloatPoint& velocity,
     const blink::WebSize& cumulative_scroll) {
-  auto curve = WebGestureCurveImpl::CreateFromDefaultPlatformCurve(
-      gfx::Vector2dF(velocity.x, velocity.y),
-      gfx::Vector2dF(cumulative_scroll.width, cumulative_scroll.height));
-  return curve.release();
+  bool is_main_thread =
+      main_thread_task_runner_.get() &&
+      main_thread_task_runner_->BelongsToCurrentThread();
+  return WebGestureCurveImpl::CreateFromDefaultPlatformCurve(
+             gfx::Vector2dF(velocity.x, velocity.y),
+             gfx::Vector2dF(cumulative_scroll.width, cumulative_scroll.height),
+             is_main_thread).release();
 }
 
 void BlinkPlatformImpl::didStartWorkerRunLoop(