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>
+
+@interface AVFoundationGlue : NSObject
+
+// This method returns YES if the OS version supports AVFoundation and the
+// AVFoundation bundle could be loaded correctly, or NO otherwise.
++ (BOOL)isAVFoundationSupported;
+
++ (NSBundle const*)avFoundationBundle;
+
++ (void*)avFoundationLibraryHandle;
+
+// Originally coming from AVCaptureDevice.h but in global namespace.
++ (NSString* const)avCaptureDeviceWasConnectedNotification;
++ (NSString* const)avCaptureDeviceWasDisconnectedNotification;
+
+// Originally coming from AVMediaFormat.h but in global namespace.
++ (NSString* const)avMediaTypeVideo;
++ (NSString* const)avMediaTypeAudio;
++ (NSString* const)avMediaTypeMuxed;
+
++ (NSString* const)readNSStringPtr:(char const* const)symbol
+                       fromLibrary:(void* const)handle;
+
+@end  // @interface AVFoundationGlue
+
+
+// Originally AVCaptureDevice and coming from AVCaptureDevice.h
+@interface CrAVCaptureDevice : NSObject
+
+- (BOOL)hasMediaType:(NSString const*)mediaType;
+
+@end
+
+@interface AVCaptureDeviceGlue : NSObject
+
++ (NSArray*)devices;
+
++ (BOOL)hasMediaType:(NSString const*)mediaType
+    forCaptureDevice:(CrAVCaptureDevice const*)device;
+
+@end
+
+#endif  // MEDIA_VIDEO_CAPTURE_MAC_AVFOUNDATION_GLUE_H_