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}

webrtc/base/bufferqueue.h

@@ -11,9 +11,51 @@
 #ifndef WEBRTC_BASE_BUFFERQUEUE_H_
 #define WEBRTC_BASE_BUFFERQUEUE_H_
 
+#include <deque>
+#include <vector>
 
-// 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/bufferqueue.h"
+#include "webrtc/base/buffer.h"
+#include "webrtc/base/constructormagic.h"
+#include "webrtc/base/criticalsection.h"
+
+namespace rtc {
+
+class BufferQueue {
+ public:
+  // Creates a buffer queue with a given capacity and default buffer size.
+  BufferQueue(size_t capacity, size_t default_size);
+  virtual ~BufferQueue();
+
+  // Return number of queued buffers.
+  size_t size() const;
+
+  // Clear the BufferQueue by moving all Buffers from |queue_| to |free_list_|.
+  void Clear();
+
+  // ReadFront will only read one buffer at a time and will truncate buffers
+  // that don't fit in the passed memory.
+  // Returns true unless no data could be returned.
+  bool ReadFront(void* data, size_t bytes, size_t* bytes_read);
+
+  // WriteBack always writes either the complete memory or nothing.
+  // Returns true unless no data could be written.
+  bool WriteBack(const void* data, size_t bytes, size_t* bytes_written);
+
+ protected:
+  // These methods are called when the state of the queue changes.
+  virtual void NotifyReadableForTest() {}
+  virtual void NotifyWritableForTest() {}
+
+ private:
+  size_t capacity_;
+  size_t default_size_;
+  CriticalSection crit_;
+  std::deque<Buffer*> queue_ GUARDED_BY(crit_);
+  std::vector<Buffer*> free_list_ GUARDED_BY(crit_);
+
+  RTC_DISALLOW_COPY_AND_ASSIGN(BufferQueue);
+};
+
+}  // namespace rtc
 
 #endif  // WEBRTC_BASE_BUFFERQUEUE_H_