Use webrtc::DesktopCapturer for screen capturer implementation.

media/video/capture/screen/shared_desktop_frame.cc

Index: media/video/capture/screen/shared_desktop_frame.cc
diff --git a/media/video/capture/screen/shared_desktop_frame.cc b/media/video/capture/screen/shared_desktop_frame.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b0a6f14faaec098c5fc0b1d03af7233652a4c7fe
--- /dev/null
+++ b/media/video/capture/screen/shared_desktop_frame.cc
@@ -0,0 +1,56 @@
+// 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/video/capture/screen/shared_desktop_frame.h"
+
+#include "base/memory/scoped_ptr.h"
+
+namespace media {
+
+class SharedDesktopFrame::Core : public base::RefCountedThreadSafe<Core> {
+ public:
+  Core(webrtc::DesktopFrame* frame) : frame_(frame) {}
+
+  webrtc::DesktopFrame* frame() { return frame_.get(); }
+
+ private:
+  friend class base::RefCountedThreadSafe<Core>;
+  virtual ~Core() {}
+
+  scoped_ptr<webrtc::DesktopFrame> frame_;
+
+  DISALLOW_COPY_AND_ASSIGN(Core);
+};
+
+SharedDesktopFrame::~SharedDesktopFrame() {}
+
+// static
+SharedDesktopFrame* SharedDesktopFrame::Wrap(
+    webrtc::DesktopFrame* desktop_frame) {
+   return new SharedDesktopFrame(new Core(desktop_frame));
+}
+
+webrtc::DesktopFrame* SharedDesktopFrame::GetUnderlyingFrame() {
+  return core_->frame();
+}
+
+SharedDesktopFrame* SharedDesktopFrame::Share() {
+  SharedDesktopFrame* result = new SharedDesktopFrame(core_);
+  result->set_dpi(dpi());
+  result->set_capture_time_ms(capture_time_ms());
+  *result->mutable_updated_region() = updated_region();
+  return result;
+}
+
+bool SharedDesktopFrame::IsShared() {
+  return !core_->HasOneRef();
+}
+
+SharedDesktopFrame::SharedDesktopFrame(scoped_refptr<Core> core)
+    : DesktopFrame(core->frame()->size(), core->frame()->stride(),
+                   core->frame()->data(), core->frame()->shared_memory()),
+      core_(core) {
+}
+
+}  // namespace media