[TTS] Add an ACK message to SelectWordAroundCaret.

content/common/view_messages.h

Index: content/common/view_messages.h
diff --git a/content/common/view_messages.h b/content/common/view_messages.h
index 8828d5248cd17166a385b8a7762ffaa2ec67f514..4f6de7a2ce5090f4dedf5a8ed422d957c68ef978 100644
--- a/content/common/view_messages.h
+++ b/content/common/view_messages.h
@@ -882,6 +882,13 @@ IPC_MESSAGE_ROUTED2(ViewHostMsg_ShowUnhandledTapUIIfNeeded,
                     int /* x */,
                     int /* y */)
 
+// Acknowledges that a SelectWordAroundCaret completed with the specified
+// result and adjustments to the selection offsets.
+IPC_MESSAGE_ROUTED3(ViewHostMsg_SelectWordAroundCaret_ACK,
+                    bool /* did_select */,
+                    int /* start_adjust */,
+                    int /* end_adjust */)
+
 #elif defined(OS_MACOSX)
 // Receives content of a web page as plain text.
 IPC_MESSAGE_ROUTED1(ViewMsg_GetRenderedTextCompleted, std::string)