AppRTCDemo file logging.

Adds logging macros to log logs to a file. Undeletes CircularFileStream
for that purpose.

BUG=
R=jiayl@webrtc.org, pbos@webrtc.org

Review URL: https://codereview.webrtc.org/1217473011 .

Cr-Commit-Position: refs/heads/master@{#9582}
diff --git a/talk/examples/objc/AppRTCDemo/ARDWebSocketChannel.m b/talk/examples/objc/AppRTCDemo/ARDWebSocketChannel.m
index 27dd25d..f25e9d0 100644
--- a/talk/examples/objc/AppRTCDemo/ARDWebSocketChannel.m
+++ b/talk/examples/objc/AppRTCDemo/ARDWebSocketChannel.m
@@ -27,6 +27,7 @@
 
 #import "ARDWebSocketChannel.h"
 
+#import "ARDLogging.h"
 #import "ARDUtilities.h"
 #import "SRWebSocket.h"
 
@@ -57,7 +58,7 @@
     _delegate = delegate;
     _socket = [[SRWebSocket alloc] initWithURL:url];
     _socket.delegate = self;
-    NSLog(@"Opening WebSocket.");
+    ARDLog(@"Opening WebSocket.");
     [_socket open];
   }
   return self;
@@ -104,12 +105,12 @@
     NSString *messageString =
         [[NSString alloc] initWithData:messageJSONObject
                               encoding:NSUTF8StringEncoding];
-    NSLog(@"C->WSS: %@", messageString);
+    ARDLog(@"C->WSS: %@", messageString);
     [_socket send:messageString];
   } else {
     NSString *dataString =
         [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
-    NSLog(@"C->WSS POST: %@", dataString);
+    ARDLog(@"C->WSS POST: %@", dataString);
     NSString *urlString =
         [NSString stringWithFormat:@"%@/%@/%@",
             [_restURL absoluteString], _roomId, _clientId];
@@ -126,7 +127,7 @@
     return;
   }
   [_socket close];
-  NSLog(@"C->WSS DELETE rid:%@ cid:%@", _roomId, _clientId);
+  ARDLog(@"C->WSS DELETE rid:%@ cid:%@", _roomId, _clientId);
   NSString *urlString =
       [NSString stringWithFormat:@"%@/%@/%@",
           [_restURL absoluteString], _roomId, _clientId];
@@ -140,7 +141,7 @@
 #pragma mark - SRWebSocketDelegate
 
 - (void)webSocketDidOpen:(SRWebSocket *)webSocket {
-  NSLog(@"WebSocket connection opened.");
+  ARDLog(@"WebSocket connection opened.");
   self.state = kARDSignalingChannelStateOpen;
   if (_roomId.length && _clientId.length) {
     [self registerWithCollider];
@@ -154,24 +155,24 @@
                                                   options:0
                                                     error:nil];
   if (![jsonObject isKindOfClass:[NSDictionary class]]) {
-    NSLog(@"Unexpected message: %@", jsonObject);
+    ARDLog(@"Unexpected message: %@", jsonObject);
     return;
   }
   NSDictionary *wssMessage = jsonObject;
   NSString *errorString = wssMessage[kARDWSSMessageErrorKey];
   if (errorString.length) {
-    NSLog(@"WSS error: %@", errorString);
+    ARDLog(@"WSS error: %@", errorString);
     return;
   }
   NSString *payload = wssMessage[kARDWSSMessagePayloadKey];
   ARDSignalingMessage *signalingMessage =
       [ARDSignalingMessage messageFromJSONString:payload];
-  NSLog(@"WSS->C: %@", payload);
+  ARDLog(@"WSS->C: %@", payload);
   [_delegate channel:self didReceiveMessage:signalingMessage];
 }
 
 - (void)webSocket:(SRWebSocket *)webSocket didFailWithError:(NSError *)error {
-  NSLog(@"WebSocket error: %@", error);
+  ARDLog(@"WebSocket error: %@", error);
   self.state = kARDSignalingChannelStateError;
 }
 
@@ -179,7 +180,7 @@
     didCloseWithCode:(NSInteger)code
               reason:(NSString *)reason
             wasClean:(BOOL)wasClean {
-  NSLog(@"WebSocket closed with code: %ld reason:%@ wasClean:%d",
+  ARDLog(@"WebSocket closed with code: %ld reason:%@ wasClean:%d",
       (long)code, reason, wasClean);
   NSParameterAssert(_state != kARDSignalingChannelStateError);
   self.state = kARDSignalingChannelStateClosed;
@@ -204,7 +205,7 @@
                                         error:nil];
   NSString *messageString =
       [[NSString alloc] initWithData:message encoding:NSUTF8StringEncoding];
-  NSLog(@"Registering on WSS for rid:%@ cid:%@", _roomId, _clientId);
+  ARDLog(@"Registering on WSS for rid:%@ cid:%@", _roomId, _clientId);
   // Registration can fail if server rejects it. For example, if the room is
   // full.
   [_socket send:messageString];