Implement WebContentsViewChildFrame::TakeFocus.

content/common/view_messages.h

 // Copyright (c) 2012 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 page rendering.
 // Multiply-included message file, hence no include guard.
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 760 matching lines @@
                     ViewHostMsg_SelectionBounds_Params)
 
 // Asks the browser to enumerate a directory.  This is equivalent to running
 // the file chooser in directory-enumeration mode and having the user select
 // the given directory.  The result is returned in a
 // ViewMsg_EnumerateDirectoryResponse message.
 IPC_MESSAGE_ROUTED2(ViewHostMsg_EnumerateDirectory,
                     int /* request_id */,
                     base::FilePath /* file_path */)
 
-// Tells the browser to move the focus to the next (previous if reverse is
-// true) focusable element.
+// Tells the browser to move the focus to the next (previous if reverse is true)
+// focusable element in chrome if this is the top-level view or tells an outer

[dcheng, 2017/01/12 10:19:21]

This comment is a bit confusing to me. I assume "chrome" here means the chrome
ui, and if I weren't familiar with OOPIF, I would be wondering why this comment
mentions this outer/inner web contents concept at all.

Also, I would imagine this is also used when focus transitions between
cross-process frames, right?

Perhaps wording the comment to be a more generic would be nice:
When the renderer needs the browser to transfer focus cross-process on its
behalf in the focus hierarchy. This may focus an element in the browser ui or a
cross-process frame, as appropriate.

[avallee, 2017/01/12 20:00:23]

Done.

+// WebContents to continue focus traversal after the element representing the
+// inner WebContents.
 IPC_MESSAGE_ROUTED1(ViewHostMsg_TakeFocus,
                     bool /* reverse */)
 
 // Required for opening a date/time dialog
 IPC_MESSAGE_ROUTED1(ViewHostMsg_OpenDateTimeDialog,
                     ViewHostMsg_DateTimeDialogValue_Params /* value */)
 
 // Required for updating text input state.
 IPC_MESSAGE_ROUTED1(ViewHostMsg_TextInputStateChanged,
                     content::TextInputState /* text_input_state */)
@@ skipping 121 matching lines @@
                     int /* y */)
 
 #elif defined(OS_MACOSX)
 // Receives content of a web page as plain text.
 IPC_MESSAGE_ROUTED1(ViewMsg_GetRenderedTextCompleted, std::string)
 #endif
 
 // Adding a new message? Stick to the sort order above: first platform
 // independent ViewMsg, then ifdefs for platform specific ViewMsg, then platform
 // independent ViewHostMsg, then ifdefs for platform specific ViewHostMsg.