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/common/ARDLogging.mm b/talk/examples/objc/AppRTCDemo/common/ARDLogging.mm
new file mode 100644
index 0000000..7bd773d
--- /dev/null
+++ b/talk/examples/objc/AppRTCDemo/common/ARDLogging.mm
@@ -0,0 +1,68 @@
+/*
+ * libjingle
+ * Copyright 2015 Google Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  1. Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *  2. Redistributions in binary form must reproduce the above copyright notice,
+ *     this list of conditions and the following disclaimer in the documentation
+ *     and/or other materials provided with the distribution.
+ *  3. The name of the author may not be used to endorse or promote products
+ *     derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
+ * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#import "ARDLogging.h"
+
+#include "webrtc/base/logging.h"
+
+void ARDLogInit() {
+#ifndef _DEBUG
+  // In debug builds the default level is LS_INFO and in non-debug builds it is
+  // disabled. Continue to log to console in non-debug builds, but only
+  // warnings and errors.
+  rtc::LogMessage::LogToDebug(rtc::LS_WARNING);
+#endif
+}
+
+void ARDLogToWebRTCLogger(ARDLogSeverity severity, NSString *logString) {
+  if (logString.length) {
+    const char* utf8String = logString.UTF8String;
+    switch (severity) {
+      case kARDLogSeverityVerbose:
+        LOG(LS_VERBOSE) << utf8String;
+        break;
+      case kARDLogSeverityInfo:
+        LOG(LS_INFO) << utf8String;
+        break;
+      case kARDLogSeverityWarning:
+        LOG(LS_WARNING) << utf8String;
+        break;
+      case kARDLogSeverityError:
+        LOG(LS_ERROR) << utf8String;
+        break;
+    }
+  }
+}
+
+NSString *ARDFileName(const char *filePath) {
+  NSString *nsFilePath =
+      [[NSString alloc] initWithBytesNoCopy:const_cast<char *>(filePath)
+                                     length:strlen(filePath)
+                                   encoding:NSUTF8StringEncoding
+                               freeWhenDone:NO];
+  return nsFilePath.lastPathComponent;
+}