Added AVFoundation Glue and Device Monitoring for Mac.

media/video/capture/mac/avfoundation_glue.h

+// Copyright 2013 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.
+
+// AVFoundation API is only introduced in Mac OS X > 10.6, and there is only one
+// build of Chromium, so the (potential) linking with AVFoundation has to happen
+// in runtime. For this to be clean, a AVFoundationGlue class is defined to try
+// and load these AVFoundation system libraries. If it succeeds, subsequent
+// clients can use AVFoundation via the rest of the classes declared in this
+// file.
+
+#ifndef MEDIA_VIDEO_CAPTURE_MAC_AVFOUNDATION_GLUE_H_
+#define MEDIA_VIDEO_CAPTURE_MAC_AVFOUNDATION_GLUE_H_
+
+#import <Foundation/Foundation.h>
+
+#include "base/basictypes.h"
+#include "media/base/media_export.h"
+
+class MEDIA_EXPORT AVFoundationGlue {
+ public:
+  // This method returns true if the OS version supports AVFoundation and the
+  // AVFoundation bundle could be loaded correctly, or false otherwise.
+  static bool IsAVFoundationSupported();
+
+  static NSBundle const* AVFoundationBundle();
+
+  static void* AVFoundationLibraryHandle();
+
+  // Originally coming from AVCaptureDevice.h but in global namespace.
+  static NSString* AVCaptureDeviceWasConnectedNotification();
+  static NSString* AVCaptureDeviceWasDisconnectedNotification();
+
+  // Originally coming from AVMediaFormat.h but in global namespace.
+  static NSString* AVMediaTypeVideo();
+  static NSString* AVMediaTypeAudio();
+  static NSString* AVMediaTypeMuxed();
+
+ private:
+  static NSString* ReadNSStringPtr(const char* symbol);
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(AVFoundationGlue);
+};
+
+// Originally AVCaptureDevice and coming from AVCaptureDevice.h
+@interface CrAVCaptureDevice : NSObject
+
+- (BOOL)hasMediaType:(NSString*)mediaType;
+
+- (NSString*)uniqueID;
+
+@end
+
+@interface AVCaptureDeviceGlue : NSObject
+
++ (NSArray*)devices;
+
++ (BOOL)hasMediaType:(NSString*)mediaType
+    forCaptureDevice:(CrAVCaptureDevice*)device;
+
++ (NSString*)uniqueID:(CrAVCaptureDevice*)device;
+
+@end
+
+#endif  // MEDIA_VIDEO_CAPTURE_MAC_AVFOUNDATION_GLUE_H_