Adds a way to determine id of content handler that created app

mojo/shell/content_handler_connection.h

 // Copyright 2015 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 MOJO_SHELL_CONTENT_HANDLER_CONNECTION_H_
 #define MOJO_SHELL_CONTENT_HANDLER_CONNECTION_H_
 
 #include <string>
 
 #include "mojo/application/public/interfaces/content_handler.mojom.h"
 #include "mojo/shell/capability_filter.h"
 #include "url/gurl.h"
 
 namespace mojo {
 namespace shell {
 
 class ApplicationInstance;
 class ApplicationManager;
 
 // A ContentHandlerConnection is responsible for creating and maintaining a
 // connection to an app which provides the ContentHandler service.
 // A ContentHandlerConnection can only be destroyed via CloseConnection.
 // A ContentHandlerConnection manages its own lifetime and cannot be used with
 // a scoped_ptr to avoid reentrant calls into ApplicationManager late in
 // destruction.
 class ContentHandlerConnection {
  public:
+  // |id| is a unique identifier for this content handler.
   ContentHandlerConnection(ApplicationInstance* originator,
                            ApplicationManager* manager,
                            const GURL& content_handler_url,
                            const GURL& requestor_url,
                            const std::string& qualifier,
-                           const CapabilityFilter& filter);
+                           const CapabilityFilter& filter,
+                           uint32_t id);
 
   // Closes the connection and destroys |this| object.
   void CloseConnection();
 
   ContentHandler* content_handler() { return content_handler_.get(); }
   const GURL& content_handler_url() { return content_handler_url_; }
   const std::string& content_handler_qualifier() {
     return content_handler_qualifier_;
   }
+  uint32_t id() const { return id_; }
 
  private:
   ~ContentHandlerConnection();
 
   ApplicationManager* manager_;
   GURL content_handler_url_;
   std::string content_handler_qualifier_;
   ContentHandlerPtr content_handler_;
   bool connection_closed_;
+  // The id for this content handler.
+  const uint32_t id_;
 
   DISALLOW_COPY_AND_ASSIGN(ContentHandlerConnection);
 };
 
 }  // namespace shell
 }  // namespace mojo
 
 #endif  // MOJO_SHELL_CONTENT_HANDLER_CONNECTION_H_