Android WebView: flush input events during onVSync

content/browser/renderer_host/render_widget_host_view_android.cc

Index: content/browser/renderer_host/render_widget_host_view_android.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_android.cc b/content/browser/renderer_host/render_widget_host_view_android.cc
index dd65887f78db5d47ad01b2adc5b5da168d243a18..a0437b11d2a291f0f5e51be3e6f71fa2e8c971eb 100644
--- a/content/browser/renderer_host/render_widget_host_view_android.cc
+++ b/content/browser/renderer_host/render_widget_host_view_android.cc
@@ -201,6 +201,7 @@ RenderWidgetHostViewAndroid::RenderWidgetHostViewAndroid(
       using_synchronous_compositor_(SynchronousCompositorImpl::FromID(
                                         widget_host->GetProcess()->GetID(),
                                         widget_host->GetRoutingID()) != NULL),
+      vsync_subscribers_(0),
       frame_evictor_(new DelegatedFrameEvictor(this)),
       locks_on_frame_count_(0),
       observing_root_window_(false) {

[boliu, 2014/08/20 02:54:16]

vsync_subscribers_ can replace observing_root_window_ I think?

[hush (inactive), 2014/08/20 03:47:21]

yes indeed.

@@ -260,9 +261,8 @@ void RenderWidgetHostViewAndroid::WasShown() {
   host_->WasShown(ui::LatencyInfo());
 
   if (content_view_core_ && !using_synchronous_compositor_) {
-    content_view_core_->GetWindowAndroid()->AddObserver(this);
+    SubscribeToVSync(INPUT | BEGIN_FRAME);
     content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
-    observing_root_window_ = true;
   }
 }
 
@@ -811,6 +811,10 @@ void RenderWidgetHostViewAndroid::ShowDisambiguationPopup(
 
 scoped_ptr<SyntheticGestureTarget>
 RenderWidgetHostViewAndroid::CreateSyntheticGestureTarget() {
+  DCHECK(content_view_core_);
+  if (using_synchronous_compositor_)
+    SubscribeToVSync(INPUT);
+
   return scoped_ptr<SyntheticGestureTarget>(new SyntheticGestureTargetAndroid(
       host_, content_view_core_->CreateTouchEventSynthesizer()));
 }
@@ -1470,8 +1474,7 @@ void RenderWidgetHostViewAndroid::SetContentViewCore(
     return;
 
   if (!using_synchronous_compositor_) {
-    content_view_core_->GetWindowAndroid()->AddObserver(this);
-    observing_root_window_ = true;
+    SubscribeToVSync(INPUT | BEGIN_FRAME);
     if (needs_begin_frame_)
       content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
   }
@@ -1518,17 +1521,31 @@ void RenderWidgetHostViewAndroid::OnDetachCompositor() {
   RunAckCallbacks();
 }
 
+void RenderWidgetHostViewAndroid::SubscribeToVSync(int type) {

[boliu, 2014/08/20 02:54:16]

Where is Unsubscribe?

[hush (inactive), 2014/08/20 03:47:21]

Will add it...
On 2014/08/20 02:54:16, boliu wrote:

+  if (!observing_root_window_) {
+    content_view_core_->GetWindowAndroid()->AddObserver(this);
+    observing_root_window_ = true;
+  }
+
+  vsync_subscribers_ |= type;
+  // Synchronous compositor does not request begin frames OnVSync.
+  DCHECK(using_synchronous_compositor_ && !(vsync_subscribers_ & BEGIN_FRAME));

[boliu, 2014/08/20 02:54:16]

This DCHECK can't be right. It fails if using_synchronous_compositor is false.

I think you want

DCHECK(!using_synchronous_compositor || !(vsync_subscribers_ & BEGIN_FRAME));

[hush (inactive), 2014/08/20 03:47:21]

yeah.. you are right.
Done
On 2014/08/20 02:54:16, boliu wrote:

+}
+
 void RenderWidgetHostViewAndroid::OnVSync(base::TimeTicks frame_time,
                                           base::TimeDelta vsync_period) {
   TRACE_EVENT0("cc", "RenderWidgetHostViewAndroid::OnVSync");
   if (!host_)
     return;
 
-  if (flush_input_requested_) {
+  if (vsync_subscribers_ & INPUT & flush_input_requested_) {
     flush_input_requested_ = false;
     host_->FlushInput();
   }
 
+  if (!(vsync_subscribers_ & BEGIN_FRAME))
+    return;
+
   TRACE_EVENT0("cc", "RenderWidgetHostViewAndroid::SendBeginFrame");
   base::TimeTicks display_time = frame_time + vsync_period;