Manage MIDI related objects and sessions' lifecycles correctly

content/renderer/media/midi_message_filter.h

Index: content/renderer/media/midi_message_filter.h
diff --git a/content/renderer/media/midi_message_filter.h b/content/renderer/media/midi_message_filter.h
index 8eed8abbbbd387d4017c2845ae4ef12aea9c7b33..b7678eeceb287f5d09fe3f66e6d2fdb65558a68a 100644
--- a/content/renderer/media/midi_message_filter.h
+++ b/content/renderer/media/midi_message_filter.h
@@ -5,10 +5,11 @@
 #ifndef CONTENT_RENDERER_MEDIA_MIDI_MESSAGE_FILTER_H_
 #define CONTENT_RENDERER_MEDIA_MIDI_MESSAGE_FILTER_H_
 
-#include <map>
+#include <set>
 #include <vector>
 
 #include "base/memory/scoped_ptr.h"
+#include "base/synchronization/lock.h"
 #include "content/common/content_export.h"
 #include "ipc/message_filter.h"
 #include "media/midi/midi_port_info.h"
@@ -29,9 +30,7 @@ class CONTENT_EXPORT MidiMessageFilter : public IPC::MessageFilter {
 
   // Each client registers for MIDI access here.
   // If permission is granted, then the client's
-  // addInputPort() and addOutputPort() methods will be called,
-  // giving the client access to receive and send data.
-  void StartSession(blink::WebMIDIAccessorClient* client);
+  void AddClient(blink::WebMIDIAccessorClient* client);
   void RemoveClient(blink::WebMIDIAccessorClient* client);
 
   // A client will only be able to call this method if it has a suitable
@@ -50,6 +49,14 @@ class CONTENT_EXPORT MidiMessageFilter : public IPC::MessageFilter {
   virtual ~MidiMessageFilter();
 
  private:
+  void StartSessionOnIOThread();
+
+  void SendMidiDataOnIOThread(uint32 port,
+                              const std::vector<uint8>& data,
+                              double timestamp);
+
+  void EndSessionOnIOThread();
+
   // Sends an IPC message using |sender_|.
   void Send(IPC::Message* message);
 
@@ -61,8 +68,9 @@ class CONTENT_EXPORT MidiMessageFilter : public IPC::MessageFilter {
 
   // Called when the browser process has approved (or denied) access to
   // MIDI hardware.
-  void OnSessionStarted(int client_id,
-                        media::MidiResult result,
+  // TODO(toyoshim): MidiPortInfoList objects should be notified separately
+  // port by port.
+  void OnSessionStarted(media::MidiResult result,
                         media::MidiPortInfoList inputs,
                         media::MidiPortInfoList outputs);
 
@@ -77,23 +85,12 @@ class CONTENT_EXPORT MidiMessageFilter : public IPC::MessageFilter {
   // sending too much data before knowing how much has already been sent.
   void OnAcknowledgeSentData(size_t bytes_sent);
 
-  void HandleSessionStarted(int client_id,
-                            media::MidiResult result,
-                            media::MidiPortInfoList inputs,
-                            media::MidiPortInfoList outputs);
+  void HandleClientAdded(blink::WebMIDIAccessorClient* client);
 
   void HandleDataReceived(uint32 port,
                           const std::vector<uint8>& data,
                           double timestamp);
 
-  void StartSessionOnIOThread(int client_id);
-
-  void SendMidiDataOnIOThread(uint32 port,
-                              const std::vector<uint8>& data,
-                              double timestamp);
-
-  blink::WebMIDIAccessorClient* GetClientFromId(int client_id);
-
   // IPC sender for Send(); must only be accessed on |io_message_loop_|.
   IPC::Sender* sender_;
 
@@ -103,15 +100,24 @@ class CONTENT_EXPORT MidiMessageFilter : public IPC::MessageFilter {
   // Main thread's message loop.
   scoped_refptr<base::MessageLoopProxy> main_message_loop_;
 
+  // Protects access to |clients_|, |clients_waiting_session_|, and
+  // |session_results_|.
+  base::Lock lock_;
+
   // Keeps track of all MIDI clients.
-  // We map client to "client id" used to track permission.
-  // When access has been approved, we add the input and output ports to
-  // the client, allowing it to actually receive and send MIDI data.
-  typedef std::map<blink::WebMIDIAccessorClient*, int> ClientsMap;
-  ClientsMap clients_;
-
-  // Dishes out client ids.
-  int next_available_id_;
+  typedef std::set<blink::WebMIDIAccessorClient*> ClientsSet;
+  ClientsSet clients_;
+
+  // Represents clients that are waiting for a session being open.
+  typedef std::vector<blink::WebMIDIAccessorClient*> ClientsQueue;
+  ClientsQueue clients_waiting_session_queue_;
+
+  // Represents a result on starting a session.
+  media::MidiResult session_result_;
+
+  // Holds MidiPortInfoList for input ports and output ports.
+  media::MidiPortInfoList inputs_;
+  media::MidiPortInfoList outputs_;
 
   size_t unacknowledged_bytes_sent_;