refactor EnumerateDevices to make it a persistent request.

content/renderer/media/media_stream_dispatcher.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_RENDERER_MEDIA_MEDIA_STREAM_DISPATCHER_H_
 #define CONTENT_RENDERER_MEDIA_MEDIA_STREAM_DISPATCHER_H_
 
 #include <list>
 #include <map>
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/gtest_prod_util.h"
-#include "base/message_loop.h"
+#include "base/memory/weak_ptr.h"
 #include "content/common/content_export.h"
 #include "content/common/media/media_stream_options.h"
 #include "content/public/renderer/render_view_observer.h"
 #include "content/renderer/media/media_stream_dispatcher_eventhandler.h"
 
+namespace base {
+class MessageLoopProxy;
+}  // namespace

[scherkus (not reviewing), 2012/08/02 00:14:19]

nit: you don't need to // namespace for fwd decls like this

[wjia(left Chromium), 2012/08/02 22:15:27]

Done.

+
 class RenderViewImpl;
 
 // MediaStreamDispatcher is a delegate for the Media Stream API messages.
 // MediaStreams are used by WebKit to open media devices such as Video Capture
 // and Audio input devices.
 // It's the complement of MediaStreamDispatcherHost (owned by
 // BrowserRenderProcessHost).
 class CONTENT_EXPORT MediaStreamDispatcher
     : public content::RenderViewObserver {
  public:
@@ skipping 15 matching lines @@
   // Stop a started stream. Label is the label provided in OnStreamGenerated.
   virtual void StopStream(const std::string& label);
 
   // Request to enumerate devices.
   void EnumerateDevices(
       int request_id,
       const base::WeakPtr<MediaStreamDispatcherEventHandler>& event_handler,
       media_stream::MediaStreamType type,
       const GURL& security_origin);
 
+  // Request to stop enumerating devices.
+  void StopEnumerateDevices(
+      int request_id,
+      const base::WeakPtr<MediaStreamDispatcherEventHandler>& event_handler);
+
   // Request to open a device.
   void OpenDevice(
       int request_id,
       const base::WeakPtr<MediaStreamDispatcherEventHandler>& event_handler,
       const std::string& device_id,
       media_stream::MediaStreamType type,
       const GURL& security_origin);
 
   // Close a started device. |label| is provided in OnDeviceOpened.
   void CloseDevice(const std::string& label);
@@ skipping 11 matching lines @@
   FRIEND_TEST_ALL_PREFIXES(MediaStreamDispatcherTest, BasicVideoDevice);
   FRIEND_TEST_ALL_PREFIXES(MediaStreamDispatcherTest, TestFailure);
   FRIEND_TEST_ALL_PREFIXES(MediaStreamDispatcherTest, CancelGenerateStream);
 
   struct Request;
 
   // Private class for keeping track of opened devices and who have
   // opened it.
   struct Stream;
 
+  struct EnumerationRequest {
+    EnumerationRequest(
+        const base::WeakPtr<MediaStreamDispatcherEventHandler>& handler,
+        int request_id);
+    ~EnumerationRequest();
+
+    base::WeakPtr<MediaStreamDispatcherEventHandler> handler;
+    int request_id;
+  };
+
+  // List of requests made to EnumerateDevices.
+  typedef std::list<EnumerationRequest> EnumerationRequestList;
+
+  struct EnumerationState {

[scherkus (not reviewing), 2012/08/02 00:14:19]

instead of stuffing everything into a struct how about this:

// If >= 0 then we've started (removes need for started variable)
int audio_enumeration_id_;
int video_enumeration_id_;

struct CachedDevices {
  media_stream::StreamDeviceInfoArray devices;
  std::string label;
};

EnumerationRequestList audio_requests_;
EnumerationRequestList video_requests_;

// Don't risk people forgetting to check cache_valid -- delete the
// cache when it's not valid
scoped_ptr<CachedDevices> cached_audio_devices_;
scoped_ptr<CachedDevices> cached_video_devices_;


WDYT?

[wjia(left Chromium), 2012/08/02 22:15:27]

Done.

+    EnumerationState();
+    ~EnumerationState();
+
+    bool started;
+    int ipc_id;
+    std::string label;
+    bool cache_valid;
+    media_stream::StreamDeviceInfoArray cached_device;
+    EnumerationRequestList requests;
+  };
+
   // Messages from the browser.
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
   void OnStreamGenerated(
       int request_id,
       const std::string& label,
       const media_stream::StreamDeviceInfoArray& audio_array,
       const media_stream::StreamDeviceInfoArray& video_array);
   void OnStreamGenerationFailed(int request_id);
   void OnVideoDeviceFailed(const std::string& label, int index);
   void OnAudioDeviceFailed(const std::string& label, int index);
   void OnDevicesEnumerated(
       int request_id,
+      const std::string& label,
       const media_stream::StreamDeviceInfoArray& device_array);
   void OnDevicesEnumerationFailed(int request_id);
   void OnDeviceOpened(
       int request_id,
       const std::string& label,
       const media_stream::StreamDeviceInfo& device_info);
   void OnDeviceOpenFailed(int request_id);
 
+  bool RemoveEnumerationRequest(
+      int request_id,
+      const base::WeakPtr<MediaStreamDispatcherEventHandler>& event_handler,
+      EnumerationState* state);
+
+  // Used for DCHECKs so methods calls won't execute in the wrong thread.
+  scoped_refptr<base::MessageLoopProxy> main_loop_;
+
   int next_ipc_id_;
   typedef std::map<std::string, Stream> LabelStreamMap;
   LabelStreamMap label_stream_map_;
 
+  EnumerationState audio_enumeration_state_;
+  EnumerationState video_enumeration_state_;
+
   // List of calls made to GenerateStream that has not yet completed.
   typedef std::list<Request> RequestList;
   RequestList requests_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaStreamDispatcher);
 };
 
 #endif  // CONTENT_RENDERER_MEDIA_MEDIA_STREAM_DISPATCHER_H_