refactor EnumerateDevices to make it a persistent request.

content/renderer/media/media_stream_dispatcher.h

Index: content/renderer/media/media_stream_dispatcher.h
===================================================================
--- content/renderer/media/media_stream_dispatcher.h	(revision 148913)
+++ content/renderer/media/media_stream_dispatcher.h	(working copy)
@@ -11,12 +11,16 @@
 
 #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.
@@ -52,6 +56,11 @@
       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,
@@ -83,6 +92,31 @@
   // 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(
@@ -95,6 +129,7 @@
   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(
@@ -103,10 +138,21 @@
       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_;