Make rendering timeouts work even if paint data received early

content/browser/renderer_host/render_widget_host_impl.h

 // 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.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_
 
 #include <list>
 #include <map>
 #include <string>
@@ skipping 245 matching lines @@
   void StartHangMonitorTimeout(base::TimeDelta delay);
 
   // Stops all existing hang monitor timeouts and assumes the renderer is
   // responsive.
   void StopHangMonitorTimeout();
 
   // Starts the rendering timeout, which will clear displayed graphics if
   // a new compositor frame is not received before it expires.
   void StartNewContentRenderingTimeout();
 
-  // Stops the rendering timeout and prevents it from clearing any displayed
-  // graphics.
-  void StopNewContentRenderingTimeout();
+  // Notification that a new compositor frame has been generated following
+  // a page load. This stops |new_content_rendering_timeout_|, or prevents
+  // the timer from running if the load commit message hasn't been received
+  // yet.
+  void OnFirstPaintAfterLoad();
 
   // Forwards the given message to the renderer. These are called by the view
   // when it has received a message.
   void ForwardGestureEventWithLatencyInfo(
       const blink::WebGestureEvent& gesture_event,
       const ui::LatencyInfo& ui_latency);
   void ForwardTouchEventWithLatencyInfo(
       const blink::WebTouchEvent& touch_event,
       const ui::LatencyInfo& ui_latency);
   void ForwardMouseEventWithLatencyInfo(
@@ skipping 524 matching lines @@
   scoped_ptr<SyntheticGestureController> synthetic_gesture_controller_;
 
   scoped_ptr<TouchEmulator> touch_emulator_;
 
   // Receives and handles all input events.
   scoped_ptr<InputRouter> input_router_;
 
   scoped_ptr<TimeoutMonitor> hang_monitor_timeout_;
 
   scoped_ptr<TimeoutMonitor> new_content_rendering_timeout_;
+  // This boolean is true if RenderWidgetHostImpl receives a compositor frame

[Charlie Reis, 2015/09/30 21:42:09]

nit: Add blank line above.

[kenrb, 2015/10/01 12:45:09]

Done.

+  // from a newly loaded page before OnFirstPaintAfterLoad() is called. In

[Charlie Reis, 2015/09/30 21:42:09]

Wait, that's not right.  It's true if the compositor frame is received (i.e.,
OnFirstPaintAfterLoad()) before commit (i.e.,
StartNewContentRenderingTimeout()).

Also, there's more things from my comment worth including here, like the fact it
gets reset at commit time and that these two IPCs arrive in a pair, not
interleaved with other navigations.

[kenrb, 2015/10/01 12:45:09]

Rewritten and expanded.

+  // that case |new_content_rendering_timeout_| is not needed, because the
+  // paint preceded the load commit notification.
+  bool received_paint_after_load_;
 
 #if defined(OS_WIN)
   std::list<HWND> dummy_windows_for_activation_;
 #endif
 
   RenderWidgetHostLatencyTracker latency_tracker_;
 
   int next_browser_snapshot_id_;
   using PendingSnapshotMap = std::map<int, GetSnapshotFromBrowserCallback>;
   PendingSnapshotMap pending_browser_snapshots_;
 
   // Indicates whether a RenderFramehost has ownership, in which case this
   // object does not self destroy.
   bool owned_by_render_frame_host_;
 
   // Indicates whether this RenderWidgetHost thinks is focused. This is trying
   // to match what the renderer process knows. It is different from
   // RenderWidgetHostView::HasFocus in that in that the focus request may fail,
   // causing HasFocus to return false when is_focused_ is true.
   bool is_focused_;
 
   base::WeakPtrFactory<RenderWidgetHostImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_