Added support for changing the volume of RTCAudioSource as discussed in BUG=webrtc:6533

webrtc/sdk/objc/Framework/Classes/RTCAudioSource.mm

Index: webrtc/sdk/objc/Framework/Classes/RTCAudioSource.mm
diff --git a/webrtc/sdk/objc/Framework/Classes/RTCAudioSource.mm b/webrtc/sdk/objc/Framework/Classes/RTCAudioSource.mm
index 897565244044e41433b4c05b053fb90d7fc87289..6e55281f1f468af2ee0d16a3bf2f43d064524619 100644
--- a/webrtc/sdk/objc/Framework/Classes/RTCAudioSource.mm
+++ b/webrtc/sdk/objc/Framework/Classes/RTCAudioSource.mm
@@ -38,6 +38,11 @@ - (NSString *)description {
   return [NSString stringWithFormat:@"RTCAudioSource( %p ): %@", self, stateString];
 }
 
+- (void)setVolume:(double) volume {

[tkchin_webrtc, 2016/11/28 21:29:54]

no space after (double)

[Frederik, 2016/12/01 18:54:31]

Done.

+    _volume = volume;

[tkchin_webrtc, 2016/11/28 21:29:54]

nit: 2 spaces not 4 (see other indentation in file)

[Frederik, 2016/12/01 18:54:31]

Done.

+    _nativeAudioSource->SetVolume(volume);
+}
+
 #pragma mark - Private
 
 - (rtc::scoped_refptr<webrtc::AudioSourceInterface>)nativeAudioSource {