Add SystemMonitor::GetMediaDevices()

base/system_monitor/system_monitor.h

Index: base/system_monitor/system_monitor.h
===================================================================
--- base/system_monitor/system_monitor.h	(revision 137731)
+++ base/system_monitor/system_monitor.h	(working copy)
@@ -6,7 +6,10 @@
 #define BASE_SYSTEM_MONITOR_SYSTEM_MONITOR_H_
 #pragma once
 
+#include <map>
 #include <string>
+#include <utility>
+#include <vector>
 
 #include "base/base_export.h"
 #include "base/basictypes.h"
@@ -47,6 +50,8 @@
   };
 
   typedef unsigned int DeviceIdType;
+  // (Media device name, Media device path)
+  typedef std::pair<std::string, FilePath> MediaDeviceInfo;

[vandebo (ex-Chrome), 2012/05/17 23:49:17]

Seems that this should now include id, so that we detaches come through, it's
easier to associate things.

[Lei Zhang, 2012/05/18 00:07:27]

Done.

I had it earlier, but I never used the id so I ended up removing it. Since
SystemMonitor is more general, some other caller may have a use for it.

 
   // Create SystemMonitor. Only one SystemMonitor instance per application
   // is allowed.
@@ -145,7 +150,12 @@
                                   const FilePath& path);
   void ProcessMediaDeviceDetached(const DeviceIdType& id);
 
+  // Appends info for attached media devices to |results|.
+  void GetMediaDevices(std::vector<MediaDeviceInfo>* results);

[vandebo (ex-Chrome), 2012/05/17 23:49:17]

GetAttachedMediaDevices ?

[Lei Zhang, 2012/05/18 00:07:27]

Done.

+
  private:
+  typedef std::map<base::SystemMonitor::DeviceIdType,

[vandebo (ex-Chrome), 2012/05/17 23:49:17]

Is this typedef worthwhile?  It's only used three times.

[Lei Zhang, 2012/05/18 00:07:27]

Yes, because I'd prefer not to write
"std::map<base::SystemMonitor::DeviceIdType, MediaDeviceInfo>::iterator" more
than once.

+                   MediaDeviceInfo> MediaDeviceMap;
 #if defined(OS_MACOSX)
   void PlatformInit();
   void PlatformDestroy();
@@ -180,6 +190,8 @@
   base::OneShotTimer<SystemMonitor> delayed_battery_check_;
 #endif
 
+  MediaDeviceMap media_device_map_;
+
   DISALLOW_COPY_AND_ASSIGN(SystemMonitor);
 };