Create webrtc/base/objc and move some logging code there

webrtc/base/objc/RTCLogging.mm

+/*
+ *  Copyright 2015 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#import "RTCLogging.h"
+
+#include "webrtc/base/logging.h"
+
+rtc::LoggingSeverity RTCGetNativeLoggingSeverity(RTCLoggingSeverity severity) {
+  switch (severity) {
+    case kRTCLoggingSeverityVerbose:
+      return rtc::LS_VERBOSE;
+    case kRTCLoggingSeverityInfo:
+      return rtc::LS_INFO;
+    case kRTCLoggingSeverityWarning:
+      return rtc::LS_WARNING;
+    case kRTCLoggingSeverityError:
+      return rtc::LS_ERROR;
+  }
+}
+
+void RTCLogEx(RTCLoggingSeverity severity, NSString* log_string) {
+  if (log_string.length) {
+    const char* utf8_string = log_string.UTF8String;
+    LOG_V(RTCGetNativeLoggingSeverity(severity)) << utf8_string;
+  }
+}
+
+void RTCSetMinDebugLogLevel(RTCLoggingSeverity severity) {
+  rtc::LogMessage::LogToDebug(RTCGetNativeLoggingSeverity(severity));
+}
+
+NSString* RTCFileName(const char* file_path) {
+  NSString* ns_file_path =
+      [[NSString alloc] initWithBytesNoCopy:const_cast<char*>(file_path)
+                                     length:strlen(file_path)
+                                   encoding:NSUTF8StringEncoding
+                               freeWhenDone:NO];
+  return ns_file_path.lastPathComponent;
+}
+