Expose public interface for composited selection bounds

public/platform/WebLayerTreeView.h

 /*
  * Copyright (C) 2011 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 24 matching lines @@
 
 class SkBitmap;
 
 namespace blink {
 class WebCompositeAndReadbackAsyncCallback;
 class WebGraphicsContext3D;
 class WebLayer;
 struct WebPoint;
 struct WebRect;
 struct WebRenderingStats;
+struct WebSelectionBound;
 
 class WebLayerTreeView {
 public:
     virtual ~WebLayerTreeView() { }
 
     // Initialization and lifecycle --------------------------------------
 
     // Indicates that the compositing surface used by this WebLayerTreeView is ready to use.
     // A WebLayerTreeView may request a context from its client before the surface is ready,
     // but it won't attempt to use it.
@@ skipping 63 matching lines @@
     // been added to the tree.
     virtual void registerForAnimations(WebLayer* layer) { }
 
     // Identify key layers to the compositor when using the pinch virtual viewport.
     virtual void registerViewportLayers(
         const WebLayer* pageScaleLayerLayer,
         const WebLayer* innerViewportScrollLayer,
         const WebLayer* outerViewportScrollLayer) { }
     virtual void clearViewportLayers() { }
 
+    // Used to update the active selection bounds.
+    virtual void registerSelection(const WebSelectionBound& anchor, const WebSelectionBound& focus) { }

[abarth-chromium, 2014/06/25 22:27:03]

Are there any invariants of these arguments that we should document?  For
example, is it legal to have one with type Caret and the other with type
SelectionLeft?  Can they both be SelectionRight? 

[jdduke (slow), 2014/06/25 22:58:10]

Yes, good call, I'll flesh out the comment a bit more.  In particular, anchor
and focus will be identical if one is of type Caret (this mirrors the current
|WebView::selectionBounds()| query), and you can indeed have both be of
SelectionRight type with mixed RTL/LTR selections.

+    virtual void clearSelection() { }
+
     // Debugging / dangerous ---------------------------------------------
 
     // Toggles the FPS counter in the HUD layer
     virtual void setShowFPSCounter(bool) { }
 
     // Toggles the paint rects in the HUD layer
     virtual void setShowPaintRects(bool) { }
 
     // Toggles the debug borders on layers
     virtual void setShowDebugBorders(bool) { }
 
     // Toggles continuous painting
     virtual void setContinuousPaintingEnabled(bool) { }
 
     // Toggles scroll bottleneck rects on the HUD layer
     virtual void setShowScrollBottleneckRects(bool) { }
 };
 
 } // namespace blink
 
 #endif // WebLayerTreeView_h