Revert "Move webrtc/{base => rtc_base}" (https://codereview.webrtc.org/2877023002)

Will reland in two different commits to preserve git blame history.

BUG=webrtc:7634
NOTRY=True
TBR=kwiberg@webrtc.org

Change-Id: I550da8525aeb9c5b8f96338fcf1c9714f3dcdab1
Reviewed-on: https://chromium-review.googlesource.com/554610
Reviewed-by: Henrik Kjellander <kjellander@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#18820}
diff --git a/webrtc/base/macutils.h b/webrtc/base/macutils.h
index ed0c4f5..fdcb3ee 100644
--- a/webrtc/base/macutils.h
+++ b/webrtc/base/macutils.h
@@ -8,12 +8,43 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#ifndef WEBRTC_BASE_MACUTILS_H_
-#define WEBRTC_BASE_MACUTILS_H_
+#ifndef WEBRTC_BASE_MACUTILS_H__
+#define WEBRTC_BASE_MACUTILS_H__
 
+#include <CoreFoundation/CoreFoundation.h>
+#include <string>
 
-// This header is deprecated and is just left here temporarily during
-// refactoring. See https://bugs.webrtc.org/7634 for more details.
-#include "webrtc/rtc_base/macutils.h"
+namespace rtc {
 
-#endif  // WEBRTC_BASE_MACUTILS_H_
+///////////////////////////////////////////////////////////////////////////////
+
+// Note that some of these functions work for both iOS and Mac OS X.  The ones
+// that are specific to Mac are #ifdef'ed as such.
+
+bool ToUtf8(const CFStringRef str16, std::string* str8);
+bool ToUtf16(const std::string& str8, CFStringRef* str16);
+
+#if defined(WEBRTC_MAC) && !defined(WEBRTC_IOS)
+void DecodeFourChar(UInt32 fc, std::string* out);
+
+enum MacOSVersionName {
+  kMacOSUnknown,       // ???
+  kMacOSOlder,         // 10.2-
+  kMacOSPanther,       // 10.3
+  kMacOSTiger,         // 10.4
+  kMacOSLeopard,       // 10.5
+  kMacOSSnowLeopard,   // 10.6
+  kMacOSLion,          // 10.7
+  kMacOSMountainLion,  // 10.8
+  kMacOSMavericks,     // 10.9
+  kMacOSNewer,         // 10.10+
+};
+
+MacOSVersionName GetOSVersionName();
+#endif
+
+///////////////////////////////////////////////////////////////////////////////
+
+}  // namespace rtc
+
+#endif  // WEBRTC_BASE_MACUTILS_H__