Show device attach web intent picker dialog only if we have registered services.

chrome/browser/intents/device_attached_intent_source.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 CHROME_BROWSER_INTENTS_DEVICE_ATTACHED_INTENT_SOURCE_H_
 #define CHROME_BROWSER_INTENTS_DEVICE_ATTACHED_INTENT_SOURCE_H_
 
+#include "base/memory/weak_ptr.h"
 #include "base/system_monitor/system_monitor.h"
 
 class Browser;
 
 namespace content {
 class WebContentsDelegate;
 }
 
 // Listens for media devices attached to the system. When such are detected,
 // translates the notification into a Web Intents dispatch.
 // The intent payload is:
 //   action = "chrome-extension://attach"
 //   type = "chrome-extension://filesystem"
 //   root_path = the File Path at which the device is accessible
 //   filesystem_id = registered isolated file system identifier
 class DeviceAttachedIntentSource
-    : public base::SystemMonitor::DevicesChangedObserver {
+    : public base::SystemMonitor::DevicesChangedObserver,
+      public base::SupportsWeakPtr<DeviceAttachedIntentSource> {
  public:
   DeviceAttachedIntentSource(Browser* browser,
                              content::WebContentsDelegate* delegate);
   virtual ~DeviceAttachedIntentSource();
 
   // base::SystemMonitor::DevicesChangedObserver implementation.
   virtual void OnMediaDeviceAttached(
       const std::string& id,
       const string16& name,
       base::SystemMonitor::MediaDeviceType type,
       const FilePath::StringType& location) OVERRIDE;
   virtual void OnMediaDeviceDetached(const std::string& id) OVERRIDE;
 
+  // Dispatches web intents for the attached media device specified by
+  // |device_info|.
+  void DispatchIntentsForService(
+      const base::SystemMonitor::MediaDeviceInfo& device_info);
+
  private:
   typedef std::map<std::string, base::SystemMonitor::MediaDeviceInfo>
       DeviceIdToInfoMap;
 
   // Weak pointer to browser to which intents will be dispatched.
   Browser* browser_;
   content::WebContentsDelegate* delegate_;
   DeviceIdToInfoMap device_id_map_;
 
   DISALLOW_COPY_AND_ASSIGN(DeviceAttachedIntentSource);
 };
 
 #endif  // CHROME_BROWSER_INTENTS_DEVICE_ATTACHED_INTENT_SOURCE_H_