Fix a crash when saving a <canvas> or <img> image which is large.

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 "base/memory/shared_memory.h"
 #include "base/process/process.h"
 #include "base/strings/string16.h"
@@ skipping 1182 matching lines @@
 IPC_MESSAGE_CONTROL1(ViewHostMsg_ForwardToWorker,
                      IPC::Message /* message */)
 
 // 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_CONTROL5(ViewHostMsg_DownloadUrl,
+IPC_MESSAGE_CONTROL4(ViewHostMsg_DownloadUrl,

[Ken Russell (switch to Gerrit), 2014/09/04 00:23:26]

Per other comments, I think this IPC should be left alone.

[zino, 2014/09/05 03:47:47]

I don't think we need it.
It was needed only for "save canvas" feature but introducing new API,
we don't need it anymore.

                      int /* render_view_id */,
                      GURL /* url */,
                      content::Referrer /* referrer */,
-                     base::string16 /* suggested_name */,
-                     bool /* use prompt for save location */)
+                     base::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 */)
 
 // Sent from an inactive renderer for the browser to route to the active
 // renderer, instructing it to close.
 IPC_MESSAGE_ROUTED0(ViewHostMsg_RouteCloseEvent)
 
@@ skipping 117 matching lines @@
                     content::FileChooserParams)
 
 // 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 */)
 
+// Asks the browser to save a image (for <canvas> or <img>) from a data URL.
+// Note: |data_url| is the contents of a data:URL, and that it's represented as
+// a string only to work around size limitations for GURLs in IPC messages.
+IPC_MESSAGE_CONTROL2(ViewHostMsg_SaveImageFromDataURL,
+                     int /* render_view_id */,
+                     std::string /* data_url */)
+
 // Tells the browser to move the focus to the next (previous if reverse is
 // true) focusable element.
 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.
@@ skipping 262 matching lines @@
 // Since the browser keeps handles to the allocated transport DIBs, this
 // message is sent to tell the browser that it may release them when the
 // renderer is finished with them.
 IPC_MESSAGE_CONTROL1(ViewHostMsg_FreeTransportDIB,
                      TransportDIB::Id /* DIB id */)
 #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.