Created VideoFramePool to avoid unnecessary VideoFrame alloc/free.

media/base/video_frame_pool.cc

Index: media/base/video_frame_pool.cc
diff --git a/media/base/video_frame_pool.cc b/media/base/video_frame_pool.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4c5a5e31e22d1a6ab64b7c852299640ae7f8e3df
--- /dev/null
+++ b/media/base/video_frame_pool.cc
@@ -0,0 +1,128 @@
+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "media/base/video_frame_pool.h"
+
+#include <list>
+
+#include "base/bind.h"
+#include "base/memory/ref_counted.h"
+#include "base/synchronization/lock.h"
+
+namespace media {
+
+class VideoFramePool::PoolImpl
+    : public base::RefCountedThreadSafe<VideoFramePool::PoolImpl> {
+ public:
+  PoolImpl();
+
+  // Returns a frame from the pool that matches the specified
+  // parameters or creates a new frame if no suitable frame exists in
+  // the pool. The pool is drained if no matching frame is found.
+  scoped_refptr<VideoFrame> CreateFrame(VideoFrame::Format format,
+                                        const gfx::Size& coded_size,
+                                        const gfx::Rect& visible_rect,
+                                        const gfx::Size& natural_size,
+                                        base::TimeDelta timestamp);
+
+  // Shuts down the frame pool and releases all frames in |frames_|.
+  // Once this is called frames will no longer be inserted back into
+  // |frames_|.
+  void Shutdown();
+
+  size_t GetPoolSizeForTesting() const { return frames_.size(); }
+
+ private:
+  friend class base::RefCountedThreadSafe<VideoFramePool::PoolImpl>;
+  ~PoolImpl();
+
+  // Called when the frame wrapper gets destroyed.
+  // |frame| is the actual frame that was wrapped and is placed
+  // in |frames_| by this function so it can be reused.
+  void FrameReleased(const scoped_refptr<VideoFrame>& frame);
+
+  base::Lock lock_;
+  bool is_shutdown_;
+  std::list<scoped_refptr<VideoFrame> > frames_;
+
+  DISALLOW_COPY_AND_ASSIGN(PoolImpl);
+};
+
+VideoFramePool::PoolImpl::PoolImpl() : is_shutdown_(false) {}
+
+VideoFramePool::PoolImpl::~PoolImpl() {
+  DCHECK(is_shutdown_);
+}
+
+scoped_refptr<VideoFrame> VideoFramePool::PoolImpl::CreateFrame(
+    VideoFrame::Format format,
+    const gfx::Size& coded_size,
+    const gfx::Rect& visible_rect,
+    const gfx::Size& natural_size,
+    base::TimeDelta timestamp) {
+  base::AutoLock auto_lock(lock_);
+  DCHECK(!is_shutdown_);
+
+  scoped_refptr<VideoFrame> frame;
+
+  while (!frame && !frames_.empty()) {
+      scoped_refptr<VideoFrame> pool_frame = frames_.front();
+      frames_.pop_front();
+
+      if (pool_frame->format() == format &&
+          pool_frame->coded_size() == coded_size &&
+          pool_frame->visible_rect() == visible_rect &&
+          pool_frame->natural_size() == natural_size) {
+        frame = pool_frame;
+        frame->SetTimestamp(kNoTimestamp());
+        break;
+      }
+  }
+
+  if (!frame) {
+    frame = VideoFrame::CreateFrame(
+        format, coded_size, visible_rect, natural_size, kNoTimestamp());
+  }
+
+  return VideoFrame::WrapVideoFrame(
+      frame, base::Bind(&VideoFramePool::PoolImpl::FrameReleased, this, frame));
+}
+
+void VideoFramePool::PoolImpl::Shutdown() {
+  base::AutoLock auto_lock(lock_);
+  is_shutdown_ = true;
+  frames_.clear();
+}
+
+void VideoFramePool::PoolImpl::FrameReleased(
+    const scoped_refptr<VideoFrame>& frame) {
+  base::AutoLock auto_lock(lock_);
+  if (is_shutdown_)
+    return;
+
+  frames_.push_back(frame);
+}
+
+VideoFramePool::VideoFramePool() : pool_(new PoolImpl()) {
+}
+
+VideoFramePool::~VideoFramePool() {
+  pool_->Shutdown();
+}
+
+scoped_refptr<VideoFrame> VideoFramePool::CreateFrame(
+    VideoFrame::Format format,
+    const gfx::Size& coded_size,
+    const gfx::Rect& visible_rect,
+    const gfx::Size& natural_size,
+    base::TimeDelta timestamp) {
+  return pool_->CreateFrame(format, coded_size, visible_rect, natural_size,
+                            timestamp);
+}
+
+size_t VideoFramePool::GetPoolSizeForTesting() const {
+  return pool_->GetPoolSizeForTesting();
+}
+
+}  // namespace media