Add oldest rotation type option to RTCFileLogger

talk/app/webrtc/objc/public/RTCFileLogger.h

 /*
  * 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,
@@ skipping 21 matching lines @@
 #define NS_DESIGNATED_INITIALIZER
 #endif
 
 typedef NS_ENUM(NSUInteger, RTCFileLoggerSeverity) {
   kRTCFileLoggerSeverityVerbose,
   kRTCFileLoggerSeverityInfo,
   kRTCFileLoggerSeverityWarning,
   kRTCFileLoggerSeverityError
 };
 
+typedef NS_ENUM(NSUInteger, RTCFileLoggerRotationType) {
+  kRTCFileLoggerTypeCall,
+  kRTCFileLoggerTypeApp,
+};
+
 // This class intercepts WebRTC logs and saves them to a file. The file size
 // will not exceed the given maximum bytesize. When the maximum bytesize is
-// reached logs from the beginning and the end are preserved while the middle
-// section is overwritten instead.
+// reached, logs are rotated according to the rotationType specified.
+// For kRTCFileLoggerTypeCall, logs from the beginning and the end
+// are preserved while the middle section is overwritten instead.
+// For kRTCFileLoggerTypeApp, the oldest log is overwritten.
 // This class is not threadsafe.
 @interface RTCFileLogger : NSObject
 
 // The severity level to capture. The default is kRTCFileLoggerSeverityInfo.
 @property(nonatomic, assign) RTCFileLoggerSeverity severity;
 
-// Default constructor provides default settings for dir path and file size.
+// The rotation type for this file logger. The default is
+// kRTCFileLoggerTypeCall.
+@property(nonatomic, readonly) RTCFileLoggerRotationType rotationType;
+
+// Default constructor provides default settings for dir path, file size and
+// rotation type.
 - (instancetype)init;
 
+// Create file logger with default rotation type.
+- (instancetype)initWithDirPath:(NSString *)dirPath
+                    maxFileSize:(NSUInteger)maxFileSize;
+
 - (instancetype)initWithDirPath:(NSString *)dirPath
                     maxFileSize:(NSUInteger)maxFileSize
+                   rotationType:(RTCFileLoggerRotationType)rotationType
     NS_DESIGNATED_INITIALIZER;
 
 // Starts writing WebRTC logs to disk if not already started. Overwrites any
 // existing file(s).
 - (void)start;
 
 // Stops writing WebRTC logs to disk. This method is also called on dealloc.
 - (void)stop;
 
 // Returns the current contents of the logs, or nil if start has been called
 // without a stop.
 - (NSData *)logData;
 
 @end