Notifying the Out of Process Renderer about Visibility Change of a Remote Frame

content/common/frame_messages.h

 // Copyright 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.
 
 // IPC messages for interacting with frames.
 // Multiply-included message file, hence no include guard.
 
 #include "cc/surfaces/surface_id.h"
 #include "cc/surfaces/surface_sequence.h"
 #include "content/common/content_export.h"
@@ skipping 1061 matching lines @@
 // Forwards an input event to a child.
 // TODO(nick): Temporary bridge, revisit once the browser process can route
 // input directly to subframes. http://crbug.com/339659
 IPC_MESSAGE_ROUTED1(FrameHostMsg_ForwardInputEvent,
                     IPC::WebInputEventPointer /* event */)
 
 // Tells the parent that a child's frame rect has changed (or the rect/scroll
 // position of a child's ancestor has changed).
 IPC_MESSAGE_ROUTED1(FrameHostMsg_FrameRectChanged, gfx::Rect /* frame_rect */)
 
+// Informs the child that the frame has changed visibility. This message will
+// be then forwarded to the guest WebContents.

[Charlie Reis, 2015/11/20 23:35:29]

nit: guest -> inner.

It's also not clear to me from the comment whether this IPC is specific to
GuestView cases or applies to out-of-process iframes as well.  Is the second
sentence only true in the case of an inner WebContents, but the IPC is sent for
any RenderFrameProxy?  (Please clarify.)

[EhsanK, 2015/12/07 16:10:15]

The second sentence was confusing so I removed it.
It applies to GuestView cases as well as oopif. "...message will be then
forwarded..." meant to say that if the frame corresponds to a <webview>, then
the corresponding WebContents for the guest (InnerWebContents) should be also
notified. But that is an issue to be dealt with later at
CrossProcessFrameConnector.

+IPC_MESSAGE_ROUTED1(FrameHostMsg_VisibilityChanged, bool /* visible */)
+
 // Used to tell the parent that the user right clicked on an area of the
 // content area, and a context menu should be shown for it. The params
 // object contains information about the node(s) that were selected when the
 // user right clicked.
 IPC_MESSAGE_ROUTED1(FrameHostMsg_ContextMenu, content::ContextMenuParams)
 
 // Initial drawing parameters for a child frame that has been swapped out to
 // another process.
 IPC_MESSAGE_ROUTED2(FrameHostMsg_InitializeChildFrame,
                     gfx::Rect /* frame_rect */,
@@ skipping 144 matching lines @@
 IPC_MESSAGE_ROUTED1(FrameHostMsg_ShowPopup,
                     FrameHostMsg_ShowPopup_Params)
 IPC_MESSAGE_ROUTED0(FrameHostMsg_HidePopup)
 
 #endif
 
 // Adding a new message? Stick to the sort order above: first platform
 // independent FrameMsg, then ifdefs for platform specific FrameMsg, then
 // platform independent FrameHostMsg, then ifdefs for platform specific
 // FrameHostMsg.