Implement unregisterProtocolHandler() for content layer

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 1476 matching lines @@
                      double /* expected_response_time */,
                      std::vector<char> /* data */)
 
 // Register a new handler for URL requests with the given scheme.
 IPC_MESSAGE_ROUTED4(ViewHostMsg_RegisterProtocolHandler,
                     std::string /* scheme */,
                     GURL /* url */,
                     base::string16 /* title */,
                     bool /* user_gesture */)
 
+// Unregister the registered handler for URL requests with the given scheme.
+IPC_MESSAGE_ROUTED3(ViewHostMsg_UnregisterProtocolHandler,

[jochen (gone - plz use gerrit), 2014/07/10 11:30:07]

you'll need an security review for this

+                    std::string /* scheme */,
+                    GURL /* url */,
+                    bool /* user_gesture */)
+
 // Stores new inspector setting in the profile.
 // TODO(jam): this should be in the chrome module
 IPC_MESSAGE_ROUTED2(ViewHostMsg_UpdateInspectorSetting,
                     std::string,  /* key */
                     std::string /* value */)
 
 // Puts the browser into "tab fullscreen" mode for the sending renderer.
 // See the comment in chrome/browser/ui/browser.h for more details.
 IPC_MESSAGE_ROUTED1(ViewHostMsg_ToggleFullscreen,
                     bool /* enter_fullscreen */)
@@ skipping 191 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.