Drag-and-drop: updateDragCursor

content/browser/renderer_host/render_widget_host_delegate.h

Index: content/browser/renderer_host/render_widget_host_delegate.h
diff --git a/content/browser/renderer_host/render_widget_host_delegate.h b/content/browser/renderer_host/render_widget_host_delegate.h
index 09cee961abb013eb04e4dbd82beb59e134eb3999..28893621eb37ed8c2288c1aa8621612595924564 100644
--- a/content/browser/renderer_host/render_widget_host_delegate.h
+++ b/content/browser/renderer_host/render_widget_host_delegate.h
@@ -33,6 +33,7 @@ class Size;
 namespace content {
 
 class BrowserAccessibilityManager;
+class RenderWidgetHost;
 class RenderWidgetHostImpl;
 class RenderWidgetHostInputEventRouter;
 class RenderViewHostDelegateView;
@@ -216,6 +217,10 @@ class CONTENT_EXPORT RenderWidgetHostDelegate {
   // fullscreen, and will return nullptr for those cases.
   virtual RenderWidgetHostImpl* GetFullscreenRenderWidgetHost() const;
 
+  // This is used to give the delegate a chance to filter IPC messages.
+  virtual bool OnMessageReceived(RenderWidgetHost* render_widget_host,
+                                 const IPC::Message& message);

[ncarter (slow), 2016/11/14 20:23:45]

I think it's probably better to add 1 call to RenderWidgetHostDelegate for each
message we need to migrate. Basically, handle the message in the RWH message
dispatcher, and forward it to the webcontents via a virtual method in
RenderWidgetHostDelegate.

There's two reasons why I think this. First, the OnMessageReceived pattern is
not mojo compatible (in mojo we won't be able to pass around a polymorphic
IPC::Message-like object). Since we'll have to eventually move to
one-delegate-method-per-IPC anyway, we might as well do it now.

Second, I can't easily assess the risk of forwarding all widget messages from
RenderWidget to WebContents. For popup and fullscreen widgets, it's possible
that this will have unintended consequences; if there's a message that
WebContents handles on behalf of its RenderViewHosts, that Widget happens also
to send/handle, and now WebContents will start handling them.

[paulmeyer, 2016/11/14 22:03:53]

Okay, that sounds very reasonable. Done.

+
  protected:
   virtual ~RenderWidgetHostDelegate() {}
 };