AVFoundation: Check selector when testing if max frame rate setting is supported.

media/video/capture/mac/video_capture_device_avfoundation_mac.mm

Index: media/video/capture/mac/video_capture_device_avfoundation_mac.mm
diff --git a/media/video/capture/mac/video_capture_device_avfoundation_mac.mm b/media/video/capture/mac/video_capture_device_avfoundation_mac.mm
index f780958b858da381a8f9ea2ef403648d0e401852..a6bf920a2c2e41c6bf438eee609f5f543644633c 100644
--- a/media/video/capture/mac/video_capture_device_avfoundation_mac.mm
+++ b/media/video/capture/mac/video_capture_device_avfoundation_mac.mm
@@ -164,11 +164,17 @@
 
   CrAVCaptureConnection* captureConnection = [captureVideoDataOutput_
       connectionWithMediaType:AVFoundationGlue::AVMediaTypeVideo()];
-  if ([captureConnection isVideoMinFrameDurationSupported]) {
+  // TODO(mcasas): Check selector existence, related to bugs
+  // http://crbug.com/327532 and http://crbug.com/328096.
+  if ([captureConnection
+           respondsToSelector:@selector(isVideoMinFrameDurationSupported)] &&
+      [captureConnection isVideoMinFrameDurationSupported]) {
     [captureConnection setVideoMinFrameDuration:
         CoreMediaGlue::CMTimeMake(1, frameRate)];
   }
-  if ([captureConnection isVideoMaxFrameDurationSupported]) {
+  if ([captureConnection
+           respondsToSelector:@selector(isVideoMaxFrameDurationSupported)] &&
+      [captureConnection isVideoMaxFrameDurationSupported]) {
     [captureConnection setVideoMaxFrameDuration:
         CoreMediaGlue::CMTimeMake(1, frameRate)];
   }