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

Reland the base->rtc_base without adding stub headers (will be
done in follow-up CL). This preserves git blame history of all files.

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

Change-Id: Iea3bb6f3f67b8374c96337b63e8f5aa3e6181012
Reviewed-on: https://chromium-review.googlesource.com/554611
Reviewed-by: Henrik Kjellander <kjellander@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#18821}

webrtc/rtc_base/copyonwritebuffer.cc

@@ -0,0 +1,112 @@
+/*
+ *  Copyright 2016 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.
+ */
+
+#include "webrtc/base/copyonwritebuffer.h"
+
+namespace rtc {
+
+CopyOnWriteBuffer::CopyOnWriteBuffer() {
+  RTC_DCHECK(IsConsistent());
+}
+
+CopyOnWriteBuffer::CopyOnWriteBuffer(const CopyOnWriteBuffer& buf)
+    : buffer_(buf.buffer_) {
+}
+
+CopyOnWriteBuffer::CopyOnWriteBuffer(CopyOnWriteBuffer&& buf)
+    : buffer_(std::move(buf.buffer_)) {
+}
+
+CopyOnWriteBuffer::CopyOnWriteBuffer(size_t size)
+    : buffer_(size > 0 ? new RefCountedObject<Buffer>(size) : nullptr) {
+  RTC_DCHECK(IsConsistent());
+}
+
+CopyOnWriteBuffer::CopyOnWriteBuffer(size_t size, size_t capacity)
+    : buffer_(size > 0 || capacity > 0
+          ? new RefCountedObject<Buffer>(size, capacity)
+          : nullptr) {
+  RTC_DCHECK(IsConsistent());
+}
+
+CopyOnWriteBuffer::~CopyOnWriteBuffer() = default;
+
+bool CopyOnWriteBuffer::operator==(const CopyOnWriteBuffer& buf) const {
+  // Must either use the same buffer internally or have the same contents.
+  RTC_DCHECK(IsConsistent());
+  RTC_DCHECK(buf.IsConsistent());
+  return buffer_.get() == buf.buffer_.get() ||
+      (buffer_.get() && buf.buffer_.get() &&
+      *buffer_.get() == *buf.buffer_.get());
+}
+
+void CopyOnWriteBuffer::SetSize(size_t size) {
+  RTC_DCHECK(IsConsistent());
+  if (!buffer_) {
+    if (size > 0) {
+      buffer_ = new RefCountedObject<Buffer>(size);
+    }
+    RTC_DCHECK(IsConsistent());
+    return;
+  }
+
+  // Clone data if referenced.
+  if (!buffer_->HasOneRef()) {
+    buffer_ = new RefCountedObject<Buffer>(
+        buffer_->data(),
+        std::min(buffer_->size(), size),
+        std::max(buffer_->capacity(), size));
+  }
+  buffer_->SetSize(size);
+  RTC_DCHECK(IsConsistent());
+}
+
+void CopyOnWriteBuffer::EnsureCapacity(size_t capacity) {
+  RTC_DCHECK(IsConsistent());
+  if (!buffer_) {
+    if (capacity > 0) {
+      buffer_ = new RefCountedObject<Buffer>(0, capacity);
+    }
+    RTC_DCHECK(IsConsistent());
+    return;
+  } else if (capacity <= buffer_->capacity()) {
+    return;
+  }
+
+  CloneDataIfReferenced(std::max(buffer_->capacity(), capacity));
+  buffer_->EnsureCapacity(capacity);
+  RTC_DCHECK(IsConsistent());
+}
+
+void CopyOnWriteBuffer::Clear() {
+  if (!buffer_)
+    return;
+
+  if (buffer_->HasOneRef()) {
+    buffer_->Clear();
+  } else {
+    buffer_ = new RefCountedObject<Buffer>(0, buffer_->capacity());
+  }
+  RTC_DCHECK(IsConsistent());
+}
+
+void CopyOnWriteBuffer::CloneDataIfReferenced(size_t new_capacity) {
+  if (buffer_->HasOneRef()) {
+    return;
+  }
+
+  buffer_ = new RefCountedObject<Buffer>(buffer_->data(), buffer_->size(),
+      new_capacity);
+  RTC_DCHECK(IsConsistent());
+}
+
+
+
+}  // namespace rtc