[Android] Use resource throttle instead of HandleExternalProtocol.

content/public/browser/resource_dispatcher_host_delegate.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.
 
 #ifndef CONTENT_PUBLIC_BROWSER_RESOURCE_DISPATCHER_HOST_DELEGATE_H_
 #define CONTENT_PUBLIC_BROWSER_RESOURCE_DISPATCHER_HOST_DELEGATE_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 77 matching lines @@
   // page is shown. If true is returned, the user will be prompted for
   // authentication credentials.
   virtual bool AcceptAuthRequest(net::URLRequest* request,
                                  net::AuthChallengeInfo* auth_info);
 
   // Creates a ResourceDispatcherHostLoginDelegate that asks the user for a
   // username and password.
   virtual ResourceDispatcherHostLoginDelegate* CreateLoginDelegate(
       net::AuthChallengeInfo* auth_info, net::URLRequest* request);
 
-  // Launches the url for the given tab.
-  virtual void HandleExternalProtocol(const GURL& url,
+  // Launches the url for the given tab. Returns true if an attempt to handle
+  // the url was made, e.g. by launching an app. Note that this does not
+  // guarantee that the app successfully handled it.
+  virtual bool HandleExternalProtocol(const GURL& url,
                                       int child_id,
                                       int route_id);
 
   // Returns true if we should force the given resource to be downloaded.
   // Otherwise, the content layer decides.
   virtual bool ShouldForceDownloadResource(
       const GURL& url, const std::string& mime_type);
 
   // Informs the delegate that a response has started.
   virtual void OnResponseStarted(
@@ skipping 10 matching lines @@
       ResourceResponse* response);
 
  protected:
   ResourceDispatcherHostDelegate();
   virtual ~ResourceDispatcherHostDelegate();
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_RESOURCE_DISPATCHER_HOST_DELEGATE_H_