Renamed RTCStatsReport to RTCLegacyStatsReport in objc files.

This is to avoid a naming conflict with webrtc::RTCStatsReport that is
surfaced if you try to include it in peerconnectioninterface.h.

Background: The current stats is very much non-spec-compliant. A new
stats collection API is underway that is meant to be spec-compliant.
Some classes in Chromium and webrtc/sdk/objc have spec-compliant names
but non-spec-compliant behavior. These are being renamed to "Legacy" so
that new spec-compliant classes can be added with the correct names.

BUG=chromium:627816
TBR=tkchin@webrtc.org
NOTRY=True

Review-Url: https://codereview.webrtc.org/2313943002
Cr-Commit-Position: refs/heads/master@{#14150}
diff --git a/webrtc/examples/objc/AppRTCDemo/ARDStatsBuilder.h b/webrtc/examples/objc/AppRTCDemo/ARDStatsBuilder.h
index 29bd7fc..a876b96 100644
--- a/webrtc/examples/objc/AppRTCDemo/ARDStatsBuilder.h
+++ b/webrtc/examples/objc/AppRTCDemo/ARDStatsBuilder.h
@@ -10,7 +10,7 @@
 
 #import <Foundation/Foundation.h>
 
-@class RTCStatsReport;
+@class RTCLegacyStatsReport;
 
 /** Class used to accumulate stats information into a single displayable string.
  */
@@ -24,6 +24,6 @@
 /** Parses the information in the stats report into an appropriate internal
  *  format used to generate the stats string.
  */
-- (void)parseStatsReport:(RTCStatsReport *)statsReport;
+- (void)parseStatsReport:(RTCLegacyStatsReport *)statsReport;
 
 @end