Add a comment about the behavior of ViewMsg_Replace....

chrome/common/render_messages_internal.h

 // Copyright (c) 2010 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.
 
 // This header is meant to be included in multiple passes, hence no traditional
 // header guard.
 // See ipc_message_macros.h for explanation of the macros and passes.
 
 #include <map>
 #include <string>
@@ skipping 200 matching lines @@
   // These messages are typically generated from context menus and request the
   // renderer to apply the specified operation to the current selection.
   IPC_MESSAGE_ROUTED0(ViewMsg_Undo)
   IPC_MESSAGE_ROUTED0(ViewMsg_Redo)
   IPC_MESSAGE_ROUTED0(ViewMsg_Cut)
   IPC_MESSAGE_ROUTED0(ViewMsg_Copy)
 #if defined(OS_MACOSX)
   IPC_MESSAGE_ROUTED0(ViewMsg_CopyToFindPboard)
 #endif
   IPC_MESSAGE_ROUTED0(ViewMsg_Paste)
+  // Replaces the selected region or a word around the cursor with the
+  // specified string.
   IPC_MESSAGE_ROUTED1(ViewMsg_Replace, string16)
   IPC_MESSAGE_ROUTED0(ViewMsg_ToggleSpellCheck)
   IPC_MESSAGE_ROUTED0(ViewMsg_Delete)
   IPC_MESSAGE_ROUTED0(ViewMsg_SelectAll)
   IPC_MESSAGE_ROUTED1(ViewMsg_ToggleSpellPanel, bool)
 
   // This message tells the renderer to advance to the next misspelling. It is
   // sent when the user clicks the "Find Next" button on the spelling panel.
   IPC_MESSAGE_ROUTED0(ViewMsg_AdvanceToNextMisspelling)
 
@@ skipping 1862 matching lines @@
       ViewHostMsg_SpellChecker_PlatformFillSuggestionList,
       string16 /* word */,
       std::vector<string16> /* suggestions */)
 
   // Request for text translation.
   // Used when translating a page from one language to another.
   IPC_MESSAGE_CONTROL1(ViewHostMsg_TranslateText,
                        ViewHostMsg_TranslateTextParam)
 
 IPC_END_MESSAGES(ViewHost)