Initialize AVFoundation explicitly

media/base/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, an 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_BASE_MAC_AVFOUNDATION_GLUE_H_
 #define MEDIA_BASE_MAC_AVFOUNDATION_GLUE_H_
 
+#if defined(__OBJC__)

[jam, 2015/05/26 23:13:47]

why are all these changes needed in this file? shouldn't __OBJC__ always be
defined for mac?

[tommi (sloooow) - chröme, 2015/05/27 09:11:02]

It's only defined when building .mm files, not when building .cc.  This
essentially just allows us to call non-ObjC functions declared in this file
(InitializeAVFoundation) from C++ code.

Here's another example:
https://code.google.com/p/chromium/codesearch#chromium/src/base/mac/mac_util....

 #import <Foundation/Foundation.h>
+#endif  // defined(__OBJC__)
 
 #include "base/basictypes.h"
 #include "media/base/mac/coremedia_glue.h"
 #include "media/base/media_export.h"
 
 class MEDIA_EXPORT AVFoundationGlue {
  public:
+  // Must be called on the UI thread prior to attempting to use any other
+  // AVFoundation methods.
+  static void InitializeAVFoundation();
+
   // This method returns true if the OS version supports AVFoundation and the
   // AVFoundation bundle could be loaded correctly, or false otherwise.
   static bool IsAVFoundationSupported();
 
+#if defined(__OBJC__)
   static NSBundle const* AVFoundationBundle();
 
   // 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();
 
   // Originally from AVCaptureSession.h but in global namespace.
   static NSString* AVCaptureSessionRuntimeErrorNotification();
   static NSString* AVCaptureSessionDidStopRunningNotification();
   static NSString* AVCaptureSessionErrorKey();
 
   // Originally from AVVideoSettings.h but in global namespace.
   static NSString* AVVideoScalingModeKey();
   static NSString* AVVideoScalingModeResizeAspectFill();
 
   static Class AVCaptureSessionClass();
   static Class AVCaptureVideoDataOutputClass();
+#endif  // defined(__OBJC__)
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(AVFoundationGlue);
 };
 
+#if defined(__OBJC__)
+
 // Originally AVCaptureDevice and coming from AVCaptureDevice.h
 MEDIA_EXPORT
 @interface CrAVCaptureDevice : NSObject
 
 - (BOOL)hasMediaType:(NSString*)mediaType;
 - (NSString*)uniqueID;
 - (NSString*)localizedName;
 - (BOOL)isSuspended;
 - (NSArray*)formats;
 - (int32_t)transportType;
@@ skipping 96 matching lines @@
 
 // Class to provide access to class methods of AVCaptureDeviceInput.
 MEDIA_EXPORT
 @interface AVCaptureDeviceInputGlue : NSObject
 
 + (CrAVCaptureDeviceInput*)deviceInputWithDevice:(CrAVCaptureDevice*)device
                                            error:(NSError**)outError;
 
 @end
 
+#endif  // defined(__OBJC__)
+
 #endif  // MEDIA_BASE_MAC_AVFOUNDATION_GLUE_H_