Mouse lock implementation, including the renderer side and the Windows version of the browser side.

content/renderer/render_widget.h

Index: content/renderer/render_widget.h
diff --git a/content/renderer/render_widget.h b/content/renderer/render_widget.h
index 05a7d5fcebaab2579ba321ed517f72de000ffac6..09805752a3d54eac8cbc55eb0c8e0a9c13cb4d7a 100644
--- a/content/renderer/render_widget.h
+++ b/content/renderer/render_widget.h
@@ -42,6 +42,7 @@ class PlatformCanvas;
 }
 
 namespace WebKit {
+class WebInputEvent;
 class WebMouseEvent;
 class WebWidget;
 struct WebPopupMenuInfo;
@@ -300,6 +301,12 @@ class RenderWidget : public IPC::Channel::Listener,
   // just handled.
   virtual void DidHandleKeyEvent() {}
 
+  // Called by OnHandleInputEvent() to notify subclasses that a mouse event is
+  // about to be handled.
+  // Returns true if no further handling is needed. In that case, the event
+  // won't be sent to WebKit or trigger DidHandleMouseEvent().
+  virtual bool WillHandleMouseEvent(const WebKit::WebMouseEvent& event);
+
   // Called by OnHandleInputEvent() to notify subclasses that a mouse event was
   // just handled.
   virtual void DidHandleMouseEvent(const WebKit::WebMouseEvent& event) {}