Blink Compositor Animation: Introduce CompositorAnimationHost correctly.

third_party/WebKit/Source/web/WebFrameWidgetImpl.h

 /*
  * Copyright (C) 2014 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 29 matching lines @@
 #include "public/web/WebInputMethodController.h"
 #include "web/PageWidgetDelegate.h"
 #include "web/WebFrameWidgetBase.h"
 #include "web/WebInputMethodControllerImpl.h"
 #include "web/WebLocalFrameImpl.h"
 #include "web/WebViewImpl.h"
 #include "wtf/Assertions.h"
 #include "wtf/HashSet.h"
 
 namespace blink {
+
+class CompositorAnimationHost;
 class Frame;
 class Element;
 class InspectorOverlay;
 class LocalFrame;
 class PaintLayerCompositor;
 class UserGestureToken;
 class CompositorAnimationTimeline;
 class WebLayer;
 class WebLayerTreeView;
 class WebMouseEvent;
@@ skipping 151 matching lines @@
   RefPtr<UserGestureToken> m_mouseCaptureGestureToken;
 
   // This is owned by the LayerTreeHostImpl, and should only be used on the
   // compositor thread. The LayerTreeHostImpl is indirectly owned by this
   // class so this pointer should be valid until this class is destructed.
   CrossThreadPersistent<CompositorMutatorImpl> m_mutator;
 
   WebLayerTreeView* m_layerTreeView;
   WebLayer* m_rootLayer;
   GraphicsLayer* m_rootGraphicsLayer;
+  std::unique_ptr<CompositorAnimationHost> m_compositorAnimationHost;

[jbroman, 2016/12/13 16:38:32]

Up to you, but if having a compositor animation host is the usual case then I'd
lean towards using WTF::Optional<> (or making CompositorAnimationHost support
nullability itself, but I gather we're leaning away from that). This is
approximately a pointer-to-a-pointer, which is a little much.

[loyso (OOO), 2016/12/13 22:23:35]

Yup. I was thinking about base::Oprional here. Will do that.

[loyso (OOO), 2016/12/19 04:03:12]

Since we want to replace it with a raw weak pointer (similar to
WebLayerTreeView* m_layerTreeView;) I prefer to continue with
std::unique_ptr<CompositorAnimationHost>.
Added a todo note in
https://bugs.chromium.org/p/chromium/issues/detail?id=584551

   bool m_isAcceleratedCompositingActive;
   bool m_layerTreeViewClosed;
 
   bool m_suppressNextKeypressEvent;
 
   bool m_ignoreInputEvents;
 
   // Whether the WebFrameWidget is rendering transparently.
   bool m_isTransparent;
 
   // Represents whether or not this object should process incoming IME events.
   bool m_imeAcceptEvents;
 
   static const WebInputEvent* m_currentInputEvent;
 
   WebColor m_baseBackgroundColor;
 
   SelfKeepAlive<WebFrameWidgetImpl> m_selfKeepAlive;
 };
 
 DEFINE_TYPE_CASTS(WebFrameWidgetImpl,
                   WebFrameWidgetBase,
                   widget,
                   widget->forSubframe(),
                   widget.forSubframe());
 
 }  // namespace blink
 
 #endif