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..23241dede1f939a52be44abc08d7687821d8926c 100644
--- a/content/browser/renderer_host/render_widget_host_view_android.cc
+++ b/content/browser/renderer_host/render_widget_host_view_android.cc
@@ -183,7 +183,6 @@ RenderWidgetHostViewAndroid::RenderWidgetHostViewAndroid(
     RenderWidgetHostImpl* widget_host,
     ContentViewCoreImpl* content_view_core)
     : host_(widget_host),
-      needs_begin_frame_(false),
       is_showing_(!widget_host->is_hidden()),
       content_view_core_(NULL),
       ime_adapter_android_(this),
@@ -196,14 +195,13 @@ RenderWidgetHostViewAndroid::RenderWidgetHostViewAndroid(
       gesture_text_selector_(this),
       touch_scrolling_(false),
       potentially_active_fling_count_(0),
-      flush_input_requested_(false),
       accelerated_surface_route_id_(0),
       using_synchronous_compositor_(SynchronousCompositorImpl::FromID(
                                         widget_host->GetProcess()->GetID(),
                                         widget_host->GetRoutingID()) != NULL),
+      vsync_subscribers_bitmask_(0),
       frame_evictor_(new DelegatedFrameEvictor(this)),
-      locks_on_frame_count_(0),
-      observing_root_window_(false) {
+      locks_on_frame_count_(0) {
   host_->SetView(this);
   SetContentViewCore(content_view_core);
   ImageTransportFactoryAndroid::AddObserver(this);
@@ -259,11 +257,8 @@ void RenderWidgetHostViewAndroid::WasShown() {
 
   host_->WasShown(ui::LatencyInfo());
 
-  if (content_view_core_ && !using_synchronous_compositor_) {
-    content_view_core_->GetWindowAndroid()->AddObserver(this);
-    content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
-    observing_root_window_ = true;
-  }
+  if (content_view_core_ && !using_synchronous_compositor_)
+    SubscribeToVSync(INPUT | BEGIN_FRAME);
 }
 
 void RenderWidgetHostViewAndroid::WasHidden() {
@@ -276,10 +271,8 @@ void RenderWidgetHostViewAndroid::WasHidden() {
   // utilization.
   host_->WasHidden();
 
-  if (content_view_core_ && !using_synchronous_compositor_) {
-    content_view_core_->GetWindowAndroid()->RemoveObserver(this);
-    observing_root_window_ = false;
-  }
+  if (content_view_core_ && !using_synchronous_compositor_)
+    UnsubscribeToVSync(INPUT | BEGIN_FRAME);
 }
 
 void RenderWidgetHostViewAndroid::WasResized() {
@@ -551,15 +544,15 @@ void RenderWidgetHostViewAndroid::OnDidChangeBodyBackgroundColor(
 }
 
 void RenderWidgetHostViewAndroid::OnSetNeedsBeginFrame(bool enabled) {
-  if (enabled == needs_begin_frame_)
+  if (enabled == IsSubscribedToType(BEGIN_FRAME) || !content_view_core_)

[boliu, 2014/08/20 20:30:00]

No need to check for !content_view_core_ here.

     return;
 
   TRACE_EVENT1("cc", "RenderWidgetHostViewAndroid::OnSetNeedsBeginFrame",
                "enabled", enabled);
-  if (content_view_core_ && enabled)
-    content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
-
-  needs_begin_frame_ = enabled;
+  if (enabled)
+    SubscribeToVSync(BEGIN_FRAME);
+  else
+    UnsubscribeToVSync(BEGIN_FRAME);
 }
 
 void RenderWidgetHostViewAndroid::OnStartContentIntent(
@@ -811,6 +804,10 @@ 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()));
 }
@@ -1300,11 +1297,11 @@ InputEventAckState RenderWidgetHostViewAndroid::FilterInputEvent(
 }
 
 void RenderWidgetHostViewAndroid::OnSetNeedsFlushInput() {
-  if (flush_input_requested_ || !content_view_core_)
+  if ((IsSubscribedToType(INPUT)) || !content_view_core_)
     return;
+
   TRACE_EVENT0("input", "RenderWidgetHostViewAndroid::OnSetNeedsFlushInput");

[boliu, 2014/08/20 20:30:00]

unrelated side note, this should be an instant event, requesting a vsync is fast

-  flush_input_requested_ = true;
-  content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
+  SubscribeToVSync(INPUT);
 }
 
 BrowserAccessibilityManager*
@@ -1345,9 +1342,8 @@ void RenderWidgetHostViewAndroid::SendTouchEvent(
   // 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 (content_view_core_) {

[boliu, 2014/08/20 20:30:00]

You need to rebase, I added something here to not request vsync in webview.

-    content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
-  }
+  if (content_view_core_)
+    SubscribeToVSync(BEGIN_FRAME);

[boliu, 2014/08/20 20:30:00]

This is not the same as simply calling RequestVSyncUpdate. Now any touch event
is going to start producing begin frames forever.

 }
 
 void RenderWidgetHostViewAndroid::SendMouseEvent(
@@ -1440,10 +1436,8 @@ void RenderWidgetHostViewAndroid::DidStopFlinging() {
 void RenderWidgetHostViewAndroid::SetContentViewCore(
     ContentViewCoreImpl* content_view_core) {
   RemoveLayers();
-  if (observing_root_window_ && content_view_core_) {
-    content_view_core_->GetWindowAndroid()->RemoveObserver(this);
-    observing_root_window_ = false;
-  }
+  if (vsync_subscribers_bitmask_ && content_view_core_)
+    UnsubscribeToVSync(INPUT | BEGIN_FRAME);

[boliu, 2014/08/20 20:30:00]

I think we need an catch all enum value here.

 
   bool resize = false;
   if (content_view_core != content_view_core_) {
@@ -1469,12 +1463,9 @@ void RenderWidgetHostViewAndroid::SetContentViewCore(
   if (!content_view_core_)
     return;
 
-  if (!using_synchronous_compositor_) {
-    content_view_core_->GetWindowAndroid()->AddObserver(this);
-    observing_root_window_ = true;
-    if (needs_begin_frame_)
-      content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
-  }
+  if (!using_synchronous_compositor_)
+    SubscribeToVSync(INPUT | BEGIN_FRAME);

[boliu, 2014/08/20 20:30:00]

Only subscribe to what was subscribed before.

+
 
   if (resize)
     WasResized();
@@ -1518,17 +1509,44 @@ void RenderWidgetHostViewAndroid::OnDetachCompositor() {
   RunAckCallbacks();
 }
 
+void RenderWidgetHostViewAndroid::SubscribeToVSync(uint32 type) {
+  if (!vsync_subscribers_bitmask_)
+    content_view_core_->GetWindowAndroid()->AddObserver(this);
+
+  vsync_subscribers_bitmask_ |= type;
+
+  content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
+
+  // Synchronous compositor does not request begin frames OnVSync.
+  DCHECK(!using_synchronous_compositor_ || !IsSubscribedToType(BEGIN_FRAME));
+}
+
+void RenderWidgetHostViewAndroid::UnsubscribeToVSync(uint32 type) {
+  vsync_subscribers_bitmask_ &= ~type;
+  if (!vsync_subscribers_bitmask_)
+    content_view_core_->GetWindowAndroid()->RemoveObserver(this);
+}
+
+bool RenderWidgetHostViewAndroid::IsSubscribedToType(uint32 type) {

[boliu, 2014/08/20 20:30:00]

const

+  return !!(vsync_subscribers_bitmask_ & type);
+}
+
 void RenderWidgetHostViewAndroid::OnVSync(base::TimeTicks frame_time,
                                           base::TimeDelta vsync_period) {
   TRACE_EVENT0("cc", "RenderWidgetHostViewAndroid::OnVSync");
   if (!host_)
     return;
 
-  if (flush_input_requested_) {
-    flush_input_requested_ = false;
+  if (IsSubscribedToType(INPUT)) {
+    // Need to unsubscribe before host_->FlushInput(), because FlushInput()
+    // could cause RWHVA to subscribe to input again.
+    UnsubscribeToVSync(INPUT);
     host_->FlushInput();
   }
 
+  if (!IsSubscribedToType(BEGIN_FRAME))
+    return;
+
   TRACE_EVENT0("cc", "RenderWidgetHostViewAndroid::SendBeginFrame");
   base::TimeTicks display_time = frame_time + vsync_period;
 
@@ -1543,8 +1561,7 @@ void RenderWidgetHostViewAndroid::OnVSync(base::TimeTicks frame_time,
       host_->GetRoutingID(),
       cc::BeginFrameArgs::Create(frame_time, deadline, vsync_period)));
 
-  if (needs_begin_frame_)
-    content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
+  content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();

[boliu, 2014/08/20 20:30:00]

This is still called outside of SubscribeToVSync.

 }
 
 void RenderWidgetHostViewAndroid::OnAnimate(base::TimeTicks begin_frame_time) {