Adding RenderWidgetHostViewChildFrame for OOPIF view.

content/browser/frame_host/cross_process_frame_connector.h

Index: content/browser/frame_host/cross_process_frame_connector.h
diff --git a/content/browser/frame_host/cross_process_frame_connector.h b/content/browser/frame_host/cross_process_frame_connector.h
new file mode 100644
index 0000000000000000000000000000000000000000..f2c324d875ba8c859c89dcae736e7009304a4cb0
--- /dev/null
+++ b/content/browser/frame_host/cross_process_frame_connector.h
@@ -0,0 +1,81 @@
+// Copyright (c) 2013 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_FRAME_HOST_CROSS_PROCESS_FRAME_CONNECTOR_H_
+#define CONTENT_BROWSER_FRAME_HOST_CROSS_PROCESS_FRAME_CONNECTOR_H_
+
+#include "cc/output/compositor_frame.h"
+#include "ui/gfx/rect.h"
+
+namespace IPC {
+class Message;
+}
+
+struct GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params;
+
+namespace content {
+class RenderFrameHostImpl;
+class RenderWidgetHostImpl;
+class RenderWidgetHostViewChildFrame;
+
+// -----------------------------------------------------------------------------
+// CrossProcessFrameConnector contains cached state information between a parent
+// frame and an embedded child frame that are rendered in separate processes.
+// It passes messages between them if it cannot handle the message within the
+// browser process. It is owned by the child frame's RenderFrameHostManager.
+// -----------------------------------------------------------------------------
+class CrossProcessFrameConnector {

[Charlie Reis, 2013/12/16 21:35:32]

Ok, Albert tried to explain this class to me, and I think I understand it a bit
more.  Let's see if I can summarize:

Suppose we have a top-level frame A1 (site A, frame 1), with a subframe B2. 
When painting, we need some link between the *RenderWidgetHostViewChildFrame* of
the active RenderFrameHost B2 and the swapped out *RenderFrameHost* A2.  This
allows buffer swap messages to pass between them.

The key reason this class is useful is the difference in layers: one side is a
RWHVCF, and the other is a RFH.  Normally RFHs shouldn't have direct pointers to
their RWHV.  If it weren't for that, I would argue that the RFH B2 and the RFH
A2 should point to each other (or that the RFHM should keep track of the link),
rather than introducing a new class for it.

That motivation doesn't come across in the class-level description above.  If
that's actually the reason this exists, we should clarify it in the comments to
make it easier for others to understand.

[awong, 2013/12/17 00:44:14]

I rewrote the comment. Left a TODO for ken to verify when he gets back.

+ public:
+  virtual ~CrossProcessFrameConnector();
+
+  static CrossProcessFrameConnector* CreateCrossProcessFrameConnector(

[awong, 2013/12/14 02:25:14]

Why bother with the creation method?

[awong, 2013/12/17 00:44:14]

Done.

+      RenderFrameHostImpl* frame_proxy_to_parent_renderer);
+
+  void Destroy();
+
+  bool OnMessageReceived(const IPC::Message &msg);
+
+  void SetView(RenderWidgetHostViewChildFrame* view);
+
+  // 'Platform' functionality exposed to RenderWidgetHostViewChildFrame.
+  // These methods can forward messages to the child frame proxy in the parent
+  // frame renderer or attempt to handle them within the browser process.
+  void ChildFrameBuffersSwapped(
+      const GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params& params,
+      int gpu_host_id);
+
+  void ChildFrameCompositorFrameSwapped(
+      uint32 output_surface_id,
+      scoped_ptr<cc::CompositorFrame> frame);
+
+  gfx::Rect ChildFrameRect();
+
+ private:
+  CrossProcessFrameConnector(
+      RenderFrameHostImpl* frame_proxy_to_parent_renderer);

[awong, 2013/12/14 02:25:14]

explicit

[awong, 2013/12/17 00:44:14]

Done.

+
+  // Handlers for messages received from the parent frame.
+  void OnBuffersSwappedACK(std::string mailbox_name,
+                           int route_id,
+                           int gpu_host_id,
+                           uint32 sync_point);
+
+  // The RenderFrameHostProxy that routes messages to the parent frame's

[nasko, 2013/12/16 23:16:32]

nit: RenderFrameHostProxy doesn't exist yet. Did you mean RenderFrameHostImpl?

[awong, 2013/12/17 00:44:14]

Done.

+  // renderer process. Initially NULL.
+  // TODO(kenrb): The type becomes RenderFrameProxyHost when that class comes
+  // to exist.
+  RenderFrameHostImpl* frame_proxy_to_parent_renderer_;
+
+  // The RenderWidgetHost for the child_frame. There is at most one
+  // RenderWidgetHost per frame because RenderFrameProxyHosts do
+  // not require widgets.
+  RenderWidgetHostImpl* child_frame_widget_;
+
+  gfx::Rect child_frame_rect_;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_FRAME_HOST_CROSS_PROCESS_FRAME_CONNECTOR_H_
+