Added AVFoundation Glue and Device Monitoring for Mac.

media/video/capture/mac/avfoundation_glue.mm

+// Copyright (c) 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.
+
+#import "media/video/capture/mac/avfoundation_glue.h"
+
+#include "base/mac/mac_util.h"
+
+@implementation AVFoundationGlue
+
++ (BOOL)IsAVFoundationSupported {
+  return (base::mac::IsOSLionOrLater() &&
+     [[AVFoundationGlue getAVFoundationBundle] load]);
+}
+
++ (NSBundle*)getAVFoundationBundle {
+  return [NSBundle

[Mark Mentovai, 2013/09/26 17:09:10]

This gets a new bundle each time it’s called, which kind of sucks. It should
cache it.

  static NSBundle* bundle = [NSBundle bundleWithPath:…];
  return bundle;

[mcasas, 2013/09/30 17:53:50]

Done.

+      bundleWithPath:@"/System/Library/Frameworks/AVFoundation.framework"];
+}
+
+@end  // @implementation AVFoundationGlue
+
+
+@implementation AVCaptureDeviceGlue
+
++ (NSArray *)devices {

[Mark Mentovai, 2013/09/26 17:09:10]

Same comment about consistency with spacing around your *s for pointers applies.

[mcasas, 2013/09/30 17:53:50]

Done.

+  Class avcClass = [[AVFoundationGlue getAVFoundationBundle]
+      classNamed:@"AVCaptureDevice"];
+  return [avcClass devices];
+}
+
+- (BOOL)hasMediaType:(NSString *)mediaType {
+  Class AVCaptureDeviceClass = [[AVFoundationGlue getAVFoundationBundle]

[Mark Mentovai, 2013/09/26 17:09:10]

AVCaptureDeviceClass is a local variable, and those are named with leading
lowercase letters.
http://google-styleguide.googlecode.com/svn/trunk/objcguide.xml#Variable_Names

[mcasas, 2013/09/30 17:53:50]

Done.

+      classNamed:@"AVCAptureDevice"];

[Mark Mentovai, 2013/09/26 17:09:10]

This class name is miscapitalized. Did you even test this code?

[mcasas, 2013/09/30 17:53:50]

I did but clearly this error did not show up :(, I think because finding classes
out of a library dictionary in runtime never handles errors completely correct.
This brought me to think about error handling in this case :)

+  // See http://goo.gl/hYvBs3 for an explanation of the 2 step process for

[Mark Mentovai, 2013/09/26 17:09:10]

Apple doc links go stale frequently. Don’t use shortened links for them. If you
use the whole link, at least future readers will see which doc you intended to
point to easily, and will have less of a hard time finding it.

But I think this comment is kind of obvious, so you might just not need it at
all.

[mcasas, 2013/09/30 17:53:50]

Might be obvious for you ;) but for me, having to alloc->init a class taken out
of a bundle ... :S

+  // bundle's classes access: first find it, then alloc-init.
+  id AVCaptureDeviceInstance =[[AVCaptureDeviceClass alloc] init];

[Mark Mentovai, 2013/09/26 17:09:10]

Space on each side of operators, like =.

[Mark Mentovai, 2013/09/26 17:09:10]

You alloc and init this, don’t release it or autorelease it or use a scoper, and
then leak it.

[Mark Mentovai, 2013/09/26 17:09:10]

It seems very suspicious that you would just allocate your own empty
AVCaptureDevice and then ask it if it has a media type. How is it supposed to
know? It’s anonymous, and you just created it. It doesn’t have anything to do
with a real device.

[mcasas, 2013/09/30 17:53:50]

Yes absolutely. My bad. The real way is to compose an NSInvocation and retrieve
the result of running it on the |device| input.

+  return [AVCaptureDeviceInstance hasMediaType:mediaType];
+}
+
+@end  // @implementation AVCaptureDevice