remoting/host: Rename Capturer to VideoFrameCapturer.

remoting/host/video_frame_capturer_win.cc

+// Copyright (c) 2012 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 "remoting/host/video_frame_capturer.h"
+
+#include <windows.h>
+
+#include "base/file_path.h"
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/scoped_native_library.h"
+#include "base/utf_string_conversions.h"
+#include "base/win/scoped_gdi_object.h"
+#include "remoting/base/capture_data.h"
+#include "remoting/host/video_frame_capturer_helper.h"

[Wez, 2012/07/12 15:59:22]

nit: Move below differ.h

+#include "remoting/host/desktop_win.h"
+#include "remoting/host/differ.h"
+#include "remoting/host/scoped_thread_desktop_win.h"
+#include "remoting/proto/control.pb.h"
+
+namespace remoting {
+
+namespace {
+
+// Constants from dwmapi.h.
+const UINT DWM_EC_DISABLECOMPOSITION = 0;
+const UINT DWM_EC_ENABLECOMPOSITION = 1;
+
+typedef HRESULT (WINAPI * DwmEnableCompositionFunc)(UINT);
+
+const char kDwmapiLibraryName[] = "dwmapi";
+
+// Pixel colors used when generating cursor outlines.
+const uint32 kPixelBgraBlack = 0xff000000;
+const uint32 kPixelBgraWhite = 0xffffffff;
+const uint32 kPixelBgraTransparent = 0x00000000;
+
+// VideoFrameCapturerWin captures 32bit RGB using GDI.
+//
+// VideoFrameCapturerWin is double-buffered as required by VideoFrameCapturer.
+// See remoting/host/video_frame_capturer.h.
+class VideoFrameCapturerWin : public VideoFrameCapturer {
+ public:
+  VideoFrameCapturerWin();
+  virtual ~VideoFrameCapturerWin();
+
+  // Overridden from VideoFrameCapturer:
+  virtual void Start(const CursorShapeChangedCallback& callback) OVERRIDE;
+  virtual void Stop() OVERRIDE;
+  virtual void ScreenConfigurationChanged() OVERRIDE;
+  virtual media::VideoFrame::Format pixel_format() const OVERRIDE;
+  virtual void ClearInvalidRegion() OVERRIDE;
+  virtual void InvalidateRegion(const SkRegion& invalid_region) OVERRIDE;
+  virtual void InvalidateScreen(const SkISize& size) OVERRIDE;
+  virtual void InvalidateFullScreen() OVERRIDE;
+  virtual void CaptureInvalidRegion(
+      const CaptureCompletedCallback& callback) OVERRIDE;
+  virtual const SkISize& size_most_recent() const OVERRIDE;
+
+ private:
+  struct VideoFrameBuffer {
+    VideoFrameBuffer(void* data, const SkISize& size, int bytes_per_pixel,
+                     int bytes_per_row)
+      : data(data), size(size), bytes_per_pixel(bytes_per_pixel),
+        bytes_per_row(bytes_per_row) {
+    }
+    VideoFrameBuffer() {
+      data = 0;
+      size = SkISize::Make(0, 0);
+      bytes_per_pixel = 0;
+      bytes_per_row = 0;
+    }
+    void* data;
+    SkISize size;
+    int bytes_per_pixel;
+    int bytes_per_row;
+  };
+
+  // Make sure that the current buffer has the same size as the screen.
+  void UpdateBufferCapture(const SkISize& size);
+
+  // Allocate memory for a buffer of a given size, freeing any memory previously
+  // allocated for that buffer.
+  void ReallocateBuffer(int buffer_index, const SkISize& size);
+
+  void CalculateInvalidRegion();
+  void CaptureRegion(const SkRegion& region,
+                     const CaptureCompletedCallback& callback);
+
+  void ReleaseBuffers();
+  // Generates an image in the current buffer.
+  void CaptureImage();
+
+  // Expand the cursor shape to add a white outline for visibility against
+  // dark backgrounds.
+  void AddCursorOutline(int width, int height, uint32* dst);
+
+  // Capture the current cursor shape.
+  void CaptureCursor();
+
+  // Gets the screen size.
+  SkISize GetScreenSize();
+
+  // A thread-safe list of invalid rectangles, and the size of the most
+  // recently captured screen.
+  VideoFrameCapturerHelper helper_;
+
+  // Callback notified whenever the cursor shape is changed.
+  CursorShapeChangedCallback cursor_shape_changed_callback_;
+
+  // Snapshot of the last cursor bitmap we sent to the client. This is used
+  // to diff against the current cursor so we only send a cursor-change
+  // message when the shape has changed.
+  scoped_array<uint8> last_cursor_;
+  SkISize last_cursor_size_;
+
+  // There are two buffers for the screen images, as required by Capturer.
+  static const int kNumBuffers = 2;
+  VideoFrameBuffer buffers_[kNumBuffers];
+
+  ScopedThreadDesktopWin desktop_;
+
+  // Gdi specific information about screen.
+  HWND desktop_window_;
+  HDC desktop_dc_;
+  HDC memory_dc_;
+  HBITMAP target_bitmap_[kNumBuffers];
+
+  // The screen size attached to the device contexts through which the screen
+  // is captured.
+  SkISize dc_size_;
+
+  // The current buffer with valid data for reading.
+  int current_buffer_;
+
+  // Format of pixels returned in buffer.
+  media::VideoFrame::Format pixel_format_;
+
+  // Class to calculate the difference between two screen bitmaps.
+  scoped_ptr<Differ> differ_;
+
+  base::ScopedNativeLibrary dwmapi_library_;
+  DwmEnableCompositionFunc composition_func_;
+
+  DISALLOW_COPY_AND_ASSIGN(VideoFrameCapturerWin);
+};
+
+// 3780 pixels per meter is equivalent to 96 DPI, typical on desktop monitors.
+static const int kPixelsPerMeter = 3780;
+// 32 bit RGBA is 4 bytes per pixel.
+static const int kBytesPerPixel = 4;
+
+VideoFrameCapturerWin::VideoFrameCapturerWin()
+    : last_cursor_size_(SkISize::Make(0, 0)),
+      desktop_window_(NULL),
+      desktop_dc_(NULL),
+      memory_dc_(NULL),
+      dc_size_(SkISize::Make(0, 0)),
+      current_buffer_(0),
+      pixel_format_(media::VideoFrame::RGB32),
+      composition_func_(NULL) {
+  memset(target_bitmap_, 0, sizeof(target_bitmap_));
+  memset(buffers_, 0, sizeof(buffers_));
+  ScreenConfigurationChanged();
+}
+
+VideoFrameCapturerWin::~VideoFrameCapturerWin() {
+  ReleaseBuffers();
+}
+
+media::VideoFrame::Format VideoFrameCapturerWin::pixel_format() const {
+  return pixel_format_;
+}
+
+void VideoFrameCapturerWin::ClearInvalidRegion() {
+  helper_.ClearInvalidRegion();
+}
+
+void VideoFrameCapturerWin::InvalidateRegion(const SkRegion& invalid_region) {
+  helper_.InvalidateRegion(invalid_region);
+}
+
+void VideoFrameCapturerWin::InvalidateScreen(const SkISize& size) {
+  helper_.InvalidateScreen(size);
+}
+
+void VideoFrameCapturerWin::InvalidateFullScreen() {
+  helper_.InvalidateFullScreen();
+}
+
+void VideoFrameCapturerWin::CaptureInvalidRegion(
+    const CaptureCompletedCallback& callback) {
+  // Force the system to power-up display hardware, if it has been suspended.
+  SetThreadExecutionState(ES_DISPLAY_REQUIRED);
+
+  // Perform the capture.
+  CalculateInvalidRegion();
+  SkRegion invalid_region;
+  helper_.SwapInvalidRegion(&invalid_region);
+  CaptureRegion(invalid_region, callback);
+
+  // Check for cursor shape update.
+  CaptureCursor();
+}
+
+const SkISize& VideoFrameCapturerWin::size_most_recent() const {
+  return helper_.size_most_recent();
+}
+
+void VideoFrameCapturerWin::ReleaseBuffers() {
+  for (int i = kNumBuffers - 1; i >= 0; i--) {
+    if (target_bitmap_[i]) {
+      DeleteObject(target_bitmap_[i]);
+      target_bitmap_[i] = NULL;
+    }
+    if (buffers_[i].data) {
+      DeleteObject(buffers_[i].data);
+      buffers_[i].data = NULL;
+    }
+  }
+
+  if (desktop_dc_) {
+    ReleaseDC(desktop_window_, desktop_dc_);
+    desktop_window_ = NULL;
+    desktop_dc_ = NULL;
+  }
+
+  if (memory_dc_) {
+    DeleteDC(memory_dc_);
+    memory_dc_ = NULL;
+  }
+}
+
+void VideoFrameCapturerWin::Start(
+    const CursorShapeChangedCallback& callback) {
+  cursor_shape_changed_callback_ = callback;
+
+  // Load dwmapi.dll dynamically since it is not available on XP.
+  if (!dwmapi_library_.is_valid()) {
+    FilePath path(base::GetNativeLibraryName(UTF8ToUTF16(kDwmapiLibraryName)));
+    dwmapi_library_.Reset(base::LoadNativeLibrary(path, NULL));
+  }
+
+  if (dwmapi_library_.is_valid() && composition_func_ == NULL) {
+    composition_func_ = static_cast<DwmEnableCompositionFunc>(
+        dwmapi_library_.GetFunctionPointer("DwmEnableComposition"));
+  }
+
+  // Vote to disable Aero composited desktop effects while capturing. Windows
+  // will restore Aero automatically if the process exits. This has no effect
+  // under Windows 8 or higher.  See crbug.com/124018.
+  if (composition_func_ != NULL) {
+    (*composition_func_)(DWM_EC_DISABLECOMPOSITION);
+  }
+}
+
+void VideoFrameCapturerWin::Stop() {
+  // Restore Aero.
+  if (composition_func_ != NULL) {
+    (*composition_func_)(DWM_EC_ENABLECOMPOSITION);
+  }
+}
+
+void VideoFrameCapturerWin::ScreenConfigurationChanged() {
+  // We poll for screen configuration changes, so ignore notifications.
+}
+
+void VideoFrameCapturerWin::UpdateBufferCapture(const SkISize& size) {
+  // Switch to the desktop receiving user input if different from the current
+  // one.
+  scoped_ptr<DesktopWin> input_desktop = DesktopWin::GetInputDesktop();
+  if (input_desktop.get() != NULL && !desktop_.IsSame(*input_desktop)) {
+    // Release GDI resources otherwise SetThreadDesktop will fail.
+    if (desktop_dc_) {
+      ReleaseDC(desktop_window_, desktop_dc_);
+      desktop_window_ = NULL;
+      desktop_dc_ = NULL;
+    }
+
+    if (memory_dc_) {
+      DeleteDC(memory_dc_);
+      memory_dc_ = NULL;
+    }
+
+    ReleaseBuffers();
+
+    // If SetThreadDesktop() fails, the thread is still assigned a desktop.
+    // So we can continue capture screen bits, just from a diffented desktop.
+    desktop_.SetThreadDesktop(input_desktop.Pass());
+  }
+
+  // Make sure the DCs have the correct dimensions.
+  if (size != dc_size_) {
+    // TODO(simonmorris): screen dimensions changing isn't equivalent to needing
+    // a new DC, but it's good enough for now.
+    if (desktop_dc_) {
+      ReleaseDC(desktop_window_, desktop_dc_);
+      desktop_window_ = NULL;
+      desktop_dc_ = NULL;
+    }
+
+    if (memory_dc_) {
+      DeleteDC(memory_dc_);
+      memory_dc_ = NULL;
+    }
+  }
+
+  if (desktop_dc_ == NULL) {
+    DCHECK(desktop_window_ == NULL);
+    DCHECK(memory_dc_ == NULL);
+
+    desktop_window_ = GetDesktopWindow();
+    desktop_dc_ = GetDC(desktop_window_);
+    memory_dc_ = CreateCompatibleDC(desktop_dc_);
+    dc_size_ = size;
+  }
+
+  // Make sure the current bitmap has the correct dimensions.
+  if (buffers_[current_buffer_].data == NULL ||
+      size != buffers_[current_buffer_].size) {
+    ReallocateBuffer(current_buffer_, size);
+    InvalidateFullScreen();
+  }
+}
+
+void VideoFrameCapturerWin::ReallocateBuffer(int buffer_index,
+                                             const SkISize& size) {
+  // Delete any previously constructed bitmap.
+  if (target_bitmap_[buffer_index]) {
+    DeleteObject(target_bitmap_[buffer_index]);
+    target_bitmap_[buffer_index] = NULL;
+  }
+  if (buffers_[buffer_index].data) {
+    DeleteObject(buffers_[buffer_index].data);
+    buffers_[buffer_index].data = NULL;
+  }
+
+  // Create a bitmap to keep the desktop image.
+  int rounded_width = (size.width() + 3) & (~3);
+
+  // Dimensions of screen.
+  pixel_format_ = media::VideoFrame::RGB32;
+  int bytes_per_row = rounded_width * kBytesPerPixel;
+
+  // Create a device independent bitmap (DIB) that is the same size.
+  BITMAPINFO bmi;
+  memset(&bmi, 0, sizeof(bmi));
+  bmi.bmiHeader.biHeight = -size.height();
+  bmi.bmiHeader.biWidth = rounded_width;
+  bmi.bmiHeader.biPlanes = 1;
+  bmi.bmiHeader.biBitCount = kBytesPerPixel * 8;
+  bmi.bmiHeader.biSize = sizeof(bmi.bmiHeader);
+  bmi.bmiHeader.biSizeImage = bytes_per_row * size.height();
+  bmi.bmiHeader.biXPelsPerMeter = kPixelsPerMeter;
+  bmi.bmiHeader.biYPelsPerMeter = kPixelsPerMeter;
+
+  // Create memory for the buffers.
+  target_bitmap_[buffer_index] =
+      CreateDIBSection(desktop_dc_, &bmi, DIB_RGB_COLORS,
+                       static_cast<void**>(&buffers_[buffer_index].data),
+                       NULL, 0);
+  buffers_[buffer_index].size = SkISize::Make(bmi.bmiHeader.biWidth,
+                                              std::abs(bmi.bmiHeader.biHeight));
+  buffers_[buffer_index].bytes_per_pixel = bmi.bmiHeader.biBitCount / 8;
+  buffers_[buffer_index].bytes_per_row =
+      bmi.bmiHeader.biSizeImage / std::abs(bmi.bmiHeader.biHeight);
+}
+
+void VideoFrameCapturerWin::CalculateInvalidRegion() {
+  CaptureImage();
+
+  const VideoFrameBuffer& current = buffers_[current_buffer_];
+
+  // Find the previous and current screens.
+  int prev_buffer_id = current_buffer_ - 1;
+  if (prev_buffer_id < 0) {
+    prev_buffer_id = kNumBuffers - 1;
+  }
+  const VideoFrameBuffer& prev = buffers_[prev_buffer_id];
+
+  // Maybe the previous and current screens can't be differenced.
+  if ((current.size != prev.size) ||
+      (current.bytes_per_pixel != prev.bytes_per_pixel) ||
+      (current.bytes_per_row != prev.bytes_per_row)) {
+    InvalidateScreen(current.size);
+    return;
+  }
+
+  // Make sure the differencer is set up correctly for these previous and
+  // current screens.
+  if (!differ_.get() ||
+      (differ_->width() != current.size.width()) ||
+      (differ_->height() != current.size.height()) ||
+      (differ_->bytes_per_pixel() != current.bytes_per_pixel) ||
+      (differ_->bytes_per_row() != current.bytes_per_row)) {
+    differ_.reset(new Differ(current.size.width(), current.size.height(),
+      current.bytes_per_pixel, current.bytes_per_row));
+  }
+
+  SkRegion region;
+  differ_->CalcDirtyRegion(prev.data, current.data, &region);
+
+  InvalidateRegion(region);
+}
+
+void VideoFrameCapturerWin::CaptureRegion(
+    const SkRegion& region,
+    const CaptureCompletedCallback& callback) {
+  const VideoFrameBuffer& buffer = buffers_[current_buffer_];
+  current_buffer_ = (current_buffer_ + 1) % kNumBuffers;
+
+  DataPlanes planes;
+  planes.data[0] = static_cast<uint8*>(buffer.data);
+  planes.strides[0] = buffer.bytes_per_row;
+
+  scoped_refptr<CaptureData> data(new CaptureData(planes,
+                                                  buffer.size,
+                                                  pixel_format_));
+  data->mutable_dirty_region() = region;
+
+  helper_.set_size_most_recent(data->size());
+
+  callback.Run(data);
+}
+
+void VideoFrameCapturerWin::CaptureImage() {
+  // Make sure the structures we use to capture the image have the correct size.
+  UpdateBufferCapture(GetScreenSize());
+
+  // Select the target bitmap into the memory dc.
+  SelectObject(memory_dc_, target_bitmap_[current_buffer_]);
+
+  // And then copy the rect from desktop to memory.
+  BitBlt(memory_dc_, 0, 0, buffers_[current_buffer_].size.width(),
+      buffers_[current_buffer_].size.height(), desktop_dc_, 0, 0,
+      SRCCOPY | CAPTUREBLT);
+}
+
+void VideoFrameCapturerWin::AddCursorOutline(int width,
+                                             int height,
+                                             uint32* dst) {
+  for (int y = 0; y < height; y++) {
+    for (int x = 0; x < width; x++) {
+      // If this is a transparent pixel (bgr == 0 and alpha = 0), check the
+      // neighbor pixels to see if this should be changed to an outline pixel.
+      if (*dst == kPixelBgraTransparent) {
+        // Change to white pixel if any neighbors (top, bottom, left, right)
+        // are black.
+        if ((y > 0 && dst[-width] == kPixelBgraBlack) ||
+            (y < height - 1 && dst[width] == kPixelBgraBlack) ||
+            (x > 0 && dst[-1] == kPixelBgraBlack) ||
+            (x < width - 1 && dst[1] == kPixelBgraBlack)) {
+          *dst = kPixelBgraWhite;
+        }
+      }
+      dst++;
+    }
+  }
+}
+
+void VideoFrameCapturerWin::CaptureCursor() {
+  CURSORINFO cursor_info;
+  cursor_info.cbSize = sizeof(CURSORINFO);
+  if (!GetCursorInfo(&cursor_info)) {
+    VLOG(3) << "Unable to get cursor info. Error = " << GetLastError();
+    return;
+  }
+
+  // Note that this does not need to be freed.
+  HCURSOR hcursor = cursor_info.hCursor;
+  ICONINFO iinfo;
+  if (!GetIconInfo(hcursor, &iinfo)) {
+    VLOG(3) << "Unable to get cursor icon info. Error = " << GetLastError();
+    return;
+  }
+  int hotspot_x = iinfo.xHotspot;
+  int hotspot_y = iinfo.yHotspot;
+
+  // Get the cursor bitmap.
+  base::win::ScopedBitmap hbitmap;
+  BITMAP bitmap;
+  bool color_bitmap;
+  if (iinfo.hbmColor) {
+    // Color cursor bitmap.
+    color_bitmap = true;
+    hbitmap.Set((HBITMAP)CopyImage(iinfo.hbmColor, IMAGE_BITMAP, 0, 0,
+                                   LR_CREATEDIBSECTION));
+    if (!hbitmap.Get()) {
+      VLOG(3) << "Unable to copy color cursor image. Error = "
+              << GetLastError();
+      return;
+    }
+
+    // Free the color and mask bitmaps since we only need our copy.
+    DeleteObject(iinfo.hbmColor);
+    DeleteObject(iinfo.hbmMask);
+  } else {
+    // Black and white (xor) cursor.
+    color_bitmap = false;
+    hbitmap.Set(iinfo.hbmMask);
+  }
+
+  if (!GetObject(hbitmap.Get(), sizeof(BITMAP), &bitmap)) {
+    VLOG(3) << "Unable to get cursor bitmap. Error = " << GetLastError();
+    return;
+  }
+
+  int width = bitmap.bmWidth;
+  int height = bitmap.bmHeight;
+  // For non-color cursors, the mask contains both an AND and an XOR mask and
+  // the height includes both. Thus, the width is correct, but we need to
+  // divide by 2 to get the correct mask height.
+  if (!color_bitmap) {
+    height /= 2;
+  }
+  int data_size = height * width * kBytesPerPixel;
+
+  scoped_ptr<protocol::CursorShapeInfo> cursor_proto(
+      new protocol::CursorShapeInfo());
+  cursor_proto->mutable_data()->resize(data_size);
+  uint8* cursor_dst_data = const_cast<uint8*>(reinterpret_cast<const uint8*>(
+      cursor_proto->mutable_data()->data()));
+
+  // Copy/convert cursor bitmap into format needed by chromotocol.
+  int row_bytes = bitmap.bmWidthBytes;
+  if (color_bitmap) {
+    if (bitmap.bmPlanes != 1 || bitmap.bmBitsPixel != 32) {
+      VLOG(3) << "Unsupported color cursor format. Error = " << GetLastError();
+      return;
+    }
+
+    // Cursor bitmap is stored upside-down on Windows. Flip the rows and store
+    // it in the proto.
+    uint8* cursor_src_data = reinterpret_cast<uint8*>(bitmap.bmBits);
+    uint8* src = cursor_src_data + ((height - 1) * row_bytes);
+    uint8* dst = cursor_dst_data;
+    for (int row = 0; row < height; row++) {
+      memcpy(dst, src, row_bytes);
+      dst += width * kBytesPerPixel;
+      src -= row_bytes;
+    }
+  } else {
+    if (bitmap.bmPlanes != 1 || bitmap.bmBitsPixel != 1) {
+      VLOG(3) << "Unsupported cursor mask format. Error = " << GetLastError();
+      return;
+    }
+
+    // x2 because there are 2 masks in the bitmap: AND and XOR.
+    int mask_bytes = height * row_bytes * 2;
+    scoped_array<uint8> mask(new uint8[mask_bytes]);
+    if (!GetBitmapBits(hbitmap.Get(), mask_bytes, mask.get())) {
+      VLOG(3) << "Unable to get cursor mask bits. Error = " << GetLastError();
+      return;
+    }
+    uint8* and_mask = mask.get();
+    uint8* xor_mask = mask.get() + height * row_bytes;
+    uint8* dst = cursor_dst_data;
+    bool add_outline = false;
+    for (int y = 0; y < height; y++) {
+      for (int x = 0; x < width; x++) {
+        int byte = y * row_bytes + x / 8;
+        int bit = 7 - x % 8;
+        int and = and_mask[byte] & (1 << bit);
+        int xor = xor_mask[byte] & (1 << bit);
+
+        // The two cursor masks combine as follows:
+        //  AND  XOR   Windows Result  Our result   RGB  Alpha
+        //   0    0    Black           Black         00    ff
+        //   0    1    White           White         ff    ff
+        //   1    0    Screen          Transparent   00    00
+        //   1    1    Reverse-screen  Black         00    ff
+        // Since we don't support XOR cursors, we replace the "Reverse Screen"
+        // with black. In this case, we also add an outline around the cursor
+        // so that it is visible against a dark background.
+        int rgb = (!and && xor) ? 0xff : 0x00;
+        int alpha = (and && !xor) ? 0x00 : 0xff;
+        *dst++ = rgb;
+        *dst++ = rgb;
+        *dst++ = rgb;
+        *dst++ = alpha;
+        if (and && xor) {
+          add_outline = true;
+        }
+      }
+    }
+    if (add_outline) {
+      AddCursorOutline(width, height,
+                       reinterpret_cast<uint32*>(cursor_dst_data));
+    }
+  }
+
+  // Compare the current cursor with the last one we sent to the client. If
+  // they're the same, then don't bother sending the cursor again.
+  if (last_cursor_size_.equals(width, height) &&
+      memcmp(last_cursor_.get(), cursor_dst_data, data_size) == 0) {
+    return;
+  }
+
+  VLOG(3) << "Sending updated cursor: " << width << "x" << height;
+
+  cursor_proto->set_width(width);
+  cursor_proto->set_height(height);
+  cursor_proto->set_hotspot_x(hotspot_x);
+  cursor_proto->set_hotspot_y(hotspot_y);
+
+  // Record the last cursor image that we sent to the client.
+  last_cursor_.reset(new uint8[data_size]);
+  memcpy(last_cursor_.get(), cursor_dst_data, data_size);
+  last_cursor_size_ = SkISize::Make(width, height);
+
+  cursor_shape_changed_callback_.Run(cursor_proto.Pass());
+}
+
+SkISize VideoFrameCapturerWin::GetScreenSize() {
+  return SkISize::Make(GetSystemMetrics(SM_CXSCREEN),
+                       GetSystemMetrics(SM_CYSCREEN));
+}
+
+}  // namespace
+
+// static
+VideoFrameCapturer* VideoFrameCapturer::Create() {
+  return new VideoFrameCapturerWin();
+}
+
+}  // namespace remoting