Adding AecDump functionality to AppRTCDemo for iOS

webrtc/sdk/objc/Framework/Headers/WebRTC/RTCPeerConnectionFactory.h

Index: webrtc/sdk/objc/Framework/Headers/WebRTC/RTCPeerConnectionFactory.h
diff --git a/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCPeerConnectionFactory.h b/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCPeerConnectionFactory.h
index f21c107581e9048a2f92adb94315538110b25995..76f14fdfa051ce3ad2dae7547fb362a9216b4719 100644
--- a/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCPeerConnectionFactory.h
+++ b/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCPeerConnectionFactory.h
@@ -29,6 +29,10 @@ RTC_EXPORT
 
 - (instancetype)init NS_DESIGNATED_INITIALIZER;
 
+- (BOOL) startAecDump:(NSString *)filename;

[tkchin_webrtc, 2016/08/19 17:31:42]

These are part of public APIs. Is this something we want to expose for everyone,
or do we want to make it more private?

The RTCEventLog functions were added to peerconnection directly, should this
follow the same example so all the logging functions can be in one place?

nit: 
- (BOOL)startAecDumpWithFilePath:(NSString *)filePath;

no max size?

[peah-webrtc, 2016/08/23 11:45:15]

I changed this to follow what is done in the Android counterpart to this API
(webrtc/api/android/java/src/org/webrtc/PeerConnectionFactory.java), 
i.e.,
The method takes a file descriptor and a limit, and passes this to the native
code.


I change the max size to be a parameter, but for the app I will pass -1 to
specify that there should be no limit in size for the recording.

+
+- (void)stopAecDump;
+
 /** Initialize an RTCAVFoundationVideoSource with constraints. */
 - (RTCAVFoundationVideoSource *)avFoundationVideoSourceWithConstraints:
     (nullable RTCMediaConstraints *)constraints;