[Android] Always request BeginFrame when touch received

Android's vsync listener will now only dispatch a BeginFrame message if
such was requested. This exposed a hole in our BeginFrame request
pipeline, where short-circuited touch forwarding would bypass the vsync
request. Instead, always request the BeginFrame if a touch event was
received from the platform, potentially reducing the first frame's
latency when the page lacks a touch handler.
latency.

BUG=408377

Review URL: https://codereview.chromium.org/535453002

Cr-Commit-Position: refs/heads/master@{#292992}

content/browser/renderer_host/render_widget_host_view_android.cc

@@ -683,14 +683,21 @@ bool RenderWidgetHostViewAndroid::OnTouchEvent(
     return true;
   }
 
-  // Short-circuit touch forwarding if no touch handlers exist.
-  if (!host_->ShouldForwardTouchEvent()) {
+  if (host_->ShouldForwardTouchEvent()) {
+    blink::WebTouchEvent web_event = CreateWebTouchEventFromMotionEvent(event);
+    host_->ForwardTouchEventWithLatencyInfo(web_event,
+                                            CreateLatencyInfo(web_event));
+  } else {
     const bool event_consumed = false;
     gesture_provider_.OnTouchEventAck(event_consumed);
-    return true;
   }
 
-  SendTouchEvent(CreateWebTouchEventFromMotionEvent(event));
+  // Send a proactive BeginFrame on the next vsync to reduce latency.
+  // This is good enough as long as the first touch event has Begin semantics
+  // and the actual scroll happens on the next vsync.
+  if (observing_root_window_)
+    RequestVSyncUpdate(BEGIN_FRAME);
+
   return true;
 }
 
@@ -1508,19 +1515,6 @@ void RenderWidgetHostViewAndroid::SendKeyEvent(
     host_->ForwardKeyboardEvent(event);
 }
 
-void RenderWidgetHostViewAndroid::SendTouchEvent(
-    const blink::WebTouchEvent& event) {
-  if (host_)
-    host_->ForwardTouchEventWithLatencyInfo(event, CreateLatencyInfo(event));
-
-  // Send a proactive BeginFrame on the next vsync to reduce latency.
-  // This is good enough as long as the first touch event has Begin semantics
-  // and the actual scroll happens on the next vsync.
-  // TODO: Is this actually still needed?
-  if (observing_root_window_)
-    RequestVSyncUpdate(BEGIN_FRAME);
-}
-
 void RenderWidgetHostViewAndroid::SendMouseEvent(
     const blink::WebMouseEvent& event) {
   if (host_)

content/browser/renderer_host/render_widget_host_view_android.h

@@ -224,7 +224,6 @@ class CONTENT_EXPORT RenderWidgetHostViewAndroid
   void SetContentViewCore(ContentViewCoreImpl* content_view_core);
   SkColor GetCachedBackgroundColor() const;
   void SendKeyEvent(const NativeWebKeyboardEvent& event);
-  void SendTouchEvent(const blink::WebTouchEvent& event);
   void SendMouseEvent(const blink::WebMouseEvent& event);
   void SendMouseWheelEvent(const blink::WebMouseWheelEvent& event);
   void SendGestureEvent(const blink::WebGestureEvent& event);