Android WebView: flush input events during onVSync

content/browser/renderer_host/render_widget_host_view_android.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/render_widget_host_view_android.h"
 
 #include <android/bitmap.h>
 
 #include "base/basictypes.h"
 #include "base/bind.h"
@@ skipping 1286 matching lines @@
   if (compositor)
     return compositor->HandleInputEvent(input_event);
   return INPUT_EVENT_ACK_STATE_NOT_CONSUMED;
 }
 
 void RenderWidgetHostViewAndroid::OnSetNeedsFlushInput() {
   if (flush_input_requested_ || !content_view_core_)
     return;
   TRACE_EVENT0("input", "RenderWidgetHostViewAndroid::OnSetNeedsFlushInput");
   flush_input_requested_ = true;
+
+  if (!observing_root_window_) {
+    content_view_core_->GetWindowAndroid()->AddObserver(this);

[no sievers, 2014/08/21 18:01:22]

Actually I'm not sure if this is a good idea, since it potentially breaks the
balancing of Add/Remove.

I think Jared's patch takes care of this in a better way by remembering we need
a 'vsync for flush' and requesting it when we become attached to a CVC or
visible.

[boliu, 2014/08/21 18:04:56]

Jared's patch came from this. And we should submit this first, and the clean up
after, since we might want to get this into webvew

I don't think there's a balancing problem here. It should only apply to webview
where we *don't* add observer in attach/visible.

[no sievers, 2014/08/21 18:11:00]

What if OnSetNeedsFlushInput() gets called in Chrome when the view is hidden? I
don't think this method should change the attachment state wrt to the window.

Unfortunately dealing with lifetime issues between CVC, RWHV and WindowAndroid
has previously cost us way too much time, so I'd be careful.

[boliu, 2014/08/21 18:22:52]

Hmm...webview should do what chrome does, which means not flush if it's hidden.
But webview is never hidden.

So instead of adding flush_input_requested_/using_synchronous_compositor_ checks
in show/hide/attach/detach, we can just add " && using_synchronous_compositor_"
here to avoid churn...

Yeah still kinda sucks

+    observing_root_window_ = true;
+  }
+
   content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
 }
 
 BrowserAccessibilityManager*
     RenderWidgetHostViewAndroid::CreateBrowserAccessibilityManager(
         BrowserAccessibilityDelegate* delegate) {
   base::android::ScopedJavaLocalRef<jobject> obj;
   if (content_view_core_)
     obj = content_view_core_->GetJavaObject();
   return new BrowserAccessibilityManagerAndroid(
@@ skipping 205 matching lines @@
                                           base::TimeDelta vsync_period) {
   TRACE_EVENT0("cc", "RenderWidgetHostViewAndroid::OnVSync");
   if (!host_)
     return;
 
   if (flush_input_requested_) {
     flush_input_requested_ = false;
     host_->FlushInput();
   }
 
+  if (using_synchronous_compositor_)
+    return;
+
   TRACE_EVENT0("cc", "RenderWidgetHostViewAndroid::SendBeginFrame");
   base::TimeTicks display_time = frame_time + vsync_period;
 
   // TODO(brianderson): Use adaptive draw-time estimation.
   base::TimeDelta estimated_browser_composite_time =
       base::TimeDelta::FromMicroseconds(
           (1.0f * base::Time::kMicrosecondsPerSecond) / (3.0f * 60));
 
   base::TimeTicks deadline = display_time - estimated_browser_composite_time;
 
@@ skipping 149 matching lines @@
   results->orientationAngle = display.RotationAsDegree();
   results->orientationType =
       RenderWidgetHostViewBase::GetOrientationTypeForMobile(display);
   gfx::DeviceDisplayInfo info;
   results->depth = info.GetBitsPerPixel();
   results->depthPerComponent = info.GetBitsPerComponent();
   results->isMonochrome = (results->depthPerComponent == 0);
 }
 
 } // namespace content