[TTS] Add an ACK message to SelectWordAroundCaret.

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 850 matching lines @@
 IPC_MESSAGE_ROUTED1(ViewHostMsg_MoveValidationMessage,
                     gfx::Rect /* anchor rectangle in root view coordinate */)
 
 // Sent once a paint happens after the first non empty layout. In other words,
 // after the frame widget has painted something.
 IPC_MESSAGE_ROUTED0(ViewHostMsg_DidFirstVisuallyNonEmptyPaint)
 
 // Sent in reply to ViewMsg_WaitForNextFrameForTests.
 IPC_MESSAGE_ROUTED0(ViewHostMsg_WaitForNextFrameForTests_ACK)
 
+// Acknowledges that a SelectWordAroundCaret completed with the specified
+// result and adjustments to the selection offsets.
+IPC_MESSAGE_ROUTED3(ViewHostMsg_SelectWordAroundCaretAck,
+                    bool /* did_select */,
+                    int /* start_adjust */,
+                    int /* end_adjust */)
+
 #if defined(OS_ANDROID)
 // Notifies that an unhandled tap has occurred at the specified x,y position
 // and that the UI may need to be triggered.
 IPC_MESSAGE_ROUTED2(ViewHostMsg_ShowUnhandledTapUIIfNeeded,
                     int /* x */,
                     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.