Use the suggested name from an anchor's 'download' attribute.

content/common/view_messages.h

 // Copyright (c) 2011 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 "base/process.h"
 #include "base/shared_memory.h"
 #include "content/common/common_param_traits.h"
@@ skipping 1560 matching lines @@
 IPC_MESSAGE_CONTROL1(ViewHostMsg_CancelCreateDedicatedWorker,
                      int /* route_id */)
 
 // Tells the browser that a specific Appcache manifest in the current page
 // was accessed.
 IPC_MESSAGE_ROUTED2(ViewHostMsg_AppCacheAccessed,
                     GURL /* manifest url */,
                     bool /* blocked by policy */)
 
 // Initiates a download based on user actions like 'ALT+click'.
-IPC_MESSAGE_ROUTED2(ViewHostMsg_DownloadUrl,
-                    GURL /* url */,
-                    GURL /* referrer */)
+IPC_MESSAGE_ROUTED3(ViewHostMsg_DownloadUrl,
+                    GURL     /* url */,
+                    GURL     /* referrer */,
+                    string16 /* suggested_name */)
 
 // Used to go to the session history entry at the given offset (ie, -1 will
 // return the "back" item).
 IPC_MESSAGE_ROUTED1(ViewHostMsg_GoToEntryAtOffset,
                     int /* offset (from current) of history item to get */)
 
 IPC_SYNC_MESSAGE_ROUTED4_2(ViewHostMsg_RunJavaScriptMessage,
                            string16     /* in - alert message */,
                            string16     /* in - default prompt */,
                            GURL         /* in - originating page URL */,
@@ skipping 376 matching lines @@
 
 // Provide the browser process with current renderer framerate.
 IPC_MESSAGE_CONTROL2(ViewHostMsg_FPS,
                      int /* routing id */,
                      float /* frames per second */)
 
 // Notifies the browser that the page was or was not saved as MHTML.
 IPC_MESSAGE_CONTROL2(ViewHostMsg_SavedPageAsMHTML,
                      int /* job_id */,
                      bool /* success */)