remoting/host: Rename Capturer to VideoFrameCapturer.

remoting/host/video_frame_capturer_mac.mm

Index: remoting/host/video_frame_capturer_mac.mm
diff --git a/remoting/host/video_frame_capturer_mac.mm b/remoting/host/video_frame_capturer_mac.mm
new file mode 100644
index 0000000000000000000000000000000000000000..f0a79a442083cc9595a04e3d6c4174eff8c76ddb
--- /dev/null
+++ b/remoting/host/video_frame_capturer_mac.mm
@@ -0,0 +1,783 @@
+// 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 <ApplicationServices/ApplicationServices.h>
+#include <Cocoa/Cocoa.h>
+#include <dlfcn.h>
+#include <IOKit/pwr_mgt/IOPMLib.h>
+#include <OpenGL/CGLMacro.h>
+#include <OpenGL/OpenGL.h>
+#include <stddef.h>
+
+#include "base/logging.h"
+#include "base/mac/mac_util.h"
+#include "base/mac/scoped_cftyperef.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/synchronization/waitable_event.h"
+#include "base/time.h"
+#include "remoting/base/capture_data.h"
+#include "remoting/base/util.h"
+#include "remoting/host/video_frame_capturer_helper.h"
+#include "remoting/proto/control.pb.h"
+
+namespace remoting {
+
+namespace {
+
+SkIRect CGRectToSkIRect(const CGRect& rect) {
+  SkIRect sk_rect = {
+    SkScalarRound(rect.origin.x),
+    SkScalarRound(rect.origin.y),
+    SkScalarRound(rect.origin.x + rect.size.width),
+    SkScalarRound(rect.origin.y + rect.size.height)
+  };
+  return sk_rect;
+}
+
+#if (MAC_OS_X_VERSION_MIN_REQUIRED > MAC_OS_X_VERSION_10_5)
+// Possibly remove VideoFrameCapturerMac::CgBlitPreLion as well depending on
+// performance of VideoFrameCapturerMac::CgBlitPostLion on 10.6.
+#error No longer need to import CGDisplayCreateImage.
+#else
+// Declared here because CGDisplayCreateImage does not exist in the 10.5 SDK,
+// which we are currently compiling against, and it is required on 10.7 to do
+// screen capture.
+typedef CGImageRef (*CGDisplayCreateImageFunc)(CGDirectDisplayID displayID);
+#endif
+
+// The amount of time allowed for displays to reconfigure.
+const int64 kDisplayReconfigurationTimeoutInSeconds = 10;
+
+class scoped_pixel_buffer_object {
+ public:
+  scoped_pixel_buffer_object();
+  ~scoped_pixel_buffer_object();
+
+  bool Init(CGLContextObj cgl_context, int size_in_bytes);
+  void Release();
+
+  GLuint get() const { return pixel_buffer_object_; }
+
+ private:
+  CGLContextObj cgl_context_;
+  GLuint pixel_buffer_object_;
+
+  DISALLOW_COPY_AND_ASSIGN(scoped_pixel_buffer_object);
+};
+
+scoped_pixel_buffer_object::scoped_pixel_buffer_object()
+    : cgl_context_(NULL),
+      pixel_buffer_object_(0) {
+}
+
+scoped_pixel_buffer_object::~scoped_pixel_buffer_object() {
+  Release();
+}
+
+bool scoped_pixel_buffer_object::Init(CGLContextObj cgl_context,
+                                      int size_in_bytes) {
+  // The PBO path is only done on 10.6 (SnowLeopard) and above due to
+  // a driver issue that was found on 10.5
+  // (specifically on a NVIDIA GeForce 7300 GT).
+  // http://crbug.com/87283
+  if (base::mac::IsOSLeopardOrEarlier()) {
+    return false;
+  }
+  cgl_context_ = cgl_context;
+  CGLContextObj CGL_MACRO_CONTEXT = cgl_context_;
+  glGenBuffersARB(1, &pixel_buffer_object_);
+  if (glGetError() == GL_NO_ERROR) {
+    glBindBufferARB(GL_PIXEL_PACK_BUFFER_ARB, pixel_buffer_object_);
+    glBufferDataARB(GL_PIXEL_PACK_BUFFER_ARB, size_in_bytes, NULL,
+                    GL_STREAM_READ_ARB);
+    glBindBufferARB(GL_PIXEL_PACK_BUFFER_ARB, 0);
+    if (glGetError() != GL_NO_ERROR) {
+      Release();
+    }
+  } else {
+    cgl_context_ = NULL;
+    pixel_buffer_object_ = 0;
+  }
+  return pixel_buffer_object_ != 0;
+}
+
+void scoped_pixel_buffer_object::Release() {
+  if (pixel_buffer_object_) {
+    CGLContextObj CGL_MACRO_CONTEXT = cgl_context_;
+    glDeleteBuffersARB(1, &pixel_buffer_object_);
+    cgl_context_ = NULL;
+    pixel_buffer_object_ = 0;
+  }
+}
+
+// A class representing a full-frame pixel buffer.
+class VideoFrameBuffer {
+ public:
+  VideoFrameBuffer() : bytes_per_row_(0), needs_update_(true) { }
+
+  // If the buffer is marked as needing to be updated (for example after the
+  // screen mode changes) and is the wrong size, then release the old buffer
+  // and create a new one.
+  void Update() {
+    if (needs_update_) {
+      needs_update_ = false;
+      CGDirectDisplayID mainDevice = CGMainDisplayID();
+      int width = CGDisplayPixelsWide(mainDevice);
+      int height = CGDisplayPixelsHigh(mainDevice);
+      if (width != size_.width() || height != size_.height()) {
+        size_.set(width, height);
+        bytes_per_row_ = width * sizeof(uint32_t);
+        size_t buffer_size = width * height * sizeof(uint32_t);
+        ptr_.reset(new uint8[buffer_size]);
+      }
+    }
+  }
+
+  SkISize size() const { return size_; }
+  int bytes_per_row() const { return bytes_per_row_; }
+  uint8* ptr() const { return ptr_.get(); }
+
+  void set_needs_update() { needs_update_ = true; }
+
+ private:
+  SkISize size_;
+  int bytes_per_row_;
+  scoped_array<uint8> ptr_;
+  bool needs_update_;
+
+  DISALLOW_COPY_AND_ASSIGN(VideoFrameBuffer);
+};
+
+// A class to perform video frame capturing for mac.
+class VideoFrameCapturerMac : public VideoFrameCapturer {
+ public:
+  VideoFrameCapturerMac();
+  virtual ~VideoFrameCapturerMac();
+
+  bool Init();
+
+  // 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:
+  void CaptureCursor();
+
+  void GlBlitFast(const VideoFrameBuffer& buffer, const SkRegion& region);
+  void GlBlitSlow(const VideoFrameBuffer& buffer);
+  void CgBlitPreLion(const VideoFrameBuffer& buffer, const SkRegion& region);
+  void CgBlitPostLion(const VideoFrameBuffer& buffer, const SkRegion& region);
+  void CaptureRegion(const SkRegion& region,
+                     const CaptureCompletedCallback& callback);
+
+  void ScreenRefresh(CGRectCount count, const CGRect *rect_array);
+  void ScreenUpdateMove(CGScreenUpdateMoveDelta delta,
+                        size_t count,
+                        const CGRect *rect_array);
+  void DisplaysReconfigured(CGDirectDisplayID display,
+                            CGDisplayChangeSummaryFlags flags);
+  static void ScreenRefreshCallback(CGRectCount count,
+                                    const CGRect *rect_array,
+                                    void *user_parameter);
+  static void ScreenUpdateMoveCallback(CGScreenUpdateMoveDelta delta,
+                                       size_t count,
+                                       const CGRect *rect_array,
+                                       void *user_parameter);
+  static void DisplaysReconfiguredCallback(CGDirectDisplayID display,
+                                           CGDisplayChangeSummaryFlags flags,
+                                           void *user_parameter);
+
+  void ReleaseBuffers();
+
+  CGLContextObj cgl_context_;
+  static const int kNumBuffers = 2;
+  scoped_pixel_buffer_object pixel_buffer_object_;
+  VideoFrameBuffer buffers_[kNumBuffers];
+
+  // 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_;
+
+  // Image of the last cursor that we sent to the client.
+  base::mac::ScopedCFTypeRef<CGImageRef> current_cursor_;
+
+  // The current buffer with valid data for reading.
+  int current_buffer_;
+
+  // The previous buffer into which we captured, or NULL for the first capture
+  // for a particular screen resolution.
+  uint8* last_buffer_;
+
+  // Contains an invalid region from the previous capture.
+  SkRegion last_invalid_region_;
+
+  // Format of pixels returned in buffer.
+  media::VideoFrame::Format pixel_format_;
+
+  // Acts as a critical section around our display configuration data
+  // structures. Specifically cgl_context_ and pixel_buffer_object_.
+  base::WaitableEvent display_configuration_capture_event_;
+
+  // Will be non-null on lion.
+  CGDisplayCreateImageFunc display_create_image_func_;
+
+  // Power management assertion to prevent the screen from sleeping.
+  IOPMAssertionID power_assertion_id_display_;
+
+  // Power management assertion to indicate that the user is active.
+  IOPMAssertionID power_assertion_id_user_;
+
+  DISALLOW_COPY_AND_ASSIGN(VideoFrameCapturerMac);
+};
+
+VideoFrameCapturerMac::VideoFrameCapturerMac()
+    : cgl_context_(NULL),
+      current_buffer_(0),
+      last_buffer_(NULL),
+      pixel_format_(media::VideoFrame::RGB32),
+      display_configuration_capture_event_(false, true),
+      display_create_image_func_(NULL),
+      power_assertion_id_display_(kIOPMNullAssertionID),
+      power_assertion_id_user_(kIOPMNullAssertionID) {
+}
+
+VideoFrameCapturerMac::~VideoFrameCapturerMac() {
+  ReleaseBuffers();
+  CGUnregisterScreenRefreshCallback(
+      VideoFrameCapturerMac::ScreenRefreshCallback, this);
+  CGScreenUnregisterMoveCallback(
+      VideoFrameCapturerMac::ScreenUpdateMoveCallback, this);
+  CGError err = CGDisplayRemoveReconfigurationCallback(
+      VideoFrameCapturerMac::DisplaysReconfiguredCallback, this);
+  if (err != kCGErrorSuccess) {
+    LOG(ERROR) << "CGDisplayRemoveReconfigurationCallback " << err;
+  }
+}
+
+bool VideoFrameCapturerMac::Init() {
+  CGError err = CGRegisterScreenRefreshCallback(
+      VideoFrameCapturerMac::ScreenRefreshCallback, this);
+  if (err != kCGErrorSuccess) {
+    LOG(ERROR) << "CGRegisterScreenRefreshCallback " << err;
+    return false;
+  }
+
+  err = CGScreenRegisterMoveCallback(
+      VideoFrameCapturerMac::ScreenUpdateMoveCallback, this);
+  if (err != kCGErrorSuccess) {
+    LOG(ERROR) << "CGScreenRegisterMoveCallback " << err;
+    return false;
+  }
+  err = CGDisplayRegisterReconfigurationCallback(
+      VideoFrameCapturerMac::DisplaysReconfiguredCallback, this);
+  if (err != kCGErrorSuccess) {
+    LOG(ERROR) << "CGDisplayRegisterReconfigurationCallback " << err;
+    return false;
+  }
+
+  if (base::mac::IsOSLionOrLater()) {
+    display_create_image_func_ =
+        reinterpret_cast<CGDisplayCreateImageFunc>(
+            dlsym(RTLD_NEXT, "CGDisplayCreateImage"));
+    if (!display_create_image_func_) {
+      LOG(ERROR) << "Unable to load CGDisplayCreateImage on Lion";
+      return false;
+    }
+  }
+  ScreenConfigurationChanged();
+  return true;
+}
+
+void VideoFrameCapturerMac::ReleaseBuffers() {
+  if (cgl_context_) {
+    pixel_buffer_object_.Release();
+    CGLDestroyContext(cgl_context_);
+    cgl_context_ = NULL;
+  }
+  // The buffers might be in use by the encoder, so don't delete them here.
+  // Instead, mark them as "needs update"; next time the buffers are used by
+  // the capturer, they will be recreated if necessary.
+  for (int i = 0; i < kNumBuffers; ++i) {
+    buffers_[i].set_needs_update();
+  }
+}
+
+void VideoFrameCapturerMac::Start(const CursorShapeChangedCallback& callback) {
+  cursor_shape_changed_callback_ = callback;
+
+  // Create power management assertions to wake the display and prevent it from
+  // going to sleep on user idle.
+  IOPMAssertionCreate(kIOPMAssertionTypeNoDisplaySleep,
+                      kIOPMAssertionLevelOn,
+                      &power_assertion_id_display_);
+  IOPMAssertionCreate(CFSTR("UserIsActive"),
+                      kIOPMAssertionLevelOn,
+                      &power_assertion_id_user_);
+}
+
+void VideoFrameCapturerMac::Stop() {
+  if (power_assertion_id_display_ != kIOPMNullAssertionID) {
+    IOPMAssertionRelease(power_assertion_id_display_);
+    power_assertion_id_display_ = kIOPMNullAssertionID;
+  }
+  if (power_assertion_id_user_ != kIOPMNullAssertionID) {
+    IOPMAssertionRelease(power_assertion_id_user_);
+    power_assertion_id_user_ = kIOPMNullAssertionID;
+  }
+}
+
+void VideoFrameCapturerMac::ScreenConfigurationChanged() {
+  ReleaseBuffers();
+  helper_.ClearInvalidRegion();
+  last_buffer_ = NULL;
+
+  CGDirectDisplayID mainDevice = CGMainDisplayID();
+  int width = CGDisplayPixelsWide(mainDevice);
+  int height = CGDisplayPixelsHigh(mainDevice);
+  InvalidateScreen(SkISize::Make(width, height));
+
+  if (!CGDisplayUsesOpenGLAcceleration(mainDevice)) {
+    VLOG(3) << "OpenGL support not available.";
+    return;
+  }
+
+  if (display_create_image_func_ != NULL) {
+    // No need for any OpenGL support on Lion
+    return;
+  }
+
+  CGLPixelFormatAttribute attributes[] = {
+    kCGLPFAFullScreen,
+    kCGLPFADisplayMask,
+    (CGLPixelFormatAttribute)CGDisplayIDToOpenGLDisplayMask(mainDevice),
+    (CGLPixelFormatAttribute)0
+  };
+  CGLPixelFormatObj pixel_format = NULL;
+  GLint matching_pixel_format_count = 0;
+  CGLError err = CGLChoosePixelFormat(attributes,
+                                      &pixel_format,
+                                      &matching_pixel_format_count);
+  DCHECK_EQ(err, kCGLNoError);
+  err = CGLCreateContext(pixel_format, NULL, &cgl_context_);
+  DCHECK_EQ(err, kCGLNoError);
+  CGLDestroyPixelFormat(pixel_format);
+  CGLSetFullScreen(cgl_context_);
+  CGLSetCurrentContext(cgl_context_);
+
+  size_t buffer_size = width * height * sizeof(uint32_t);
+  pixel_buffer_object_.Init(cgl_context_, buffer_size);
+}
+
+media::VideoFrame::Format VideoFrameCapturerMac::pixel_format() const {
+  return pixel_format_;
+}
+
+void VideoFrameCapturerMac::ClearInvalidRegion() {
+  helper_.ClearInvalidRegion();
+}
+
+void VideoFrameCapturerMac::InvalidateRegion(const SkRegion& invalid_region) {
+  helper_.InvalidateRegion(invalid_region);
+}
+
+void VideoFrameCapturerMac::InvalidateScreen(const SkISize& size) {
+  helper_.InvalidateScreen(size);
+}
+
+void VideoFrameCapturerMac::InvalidateFullScreen() {
+  helper_.InvalidateFullScreen();
+}
+
+void VideoFrameCapturerMac::CaptureInvalidRegion(
+    const CaptureCompletedCallback& callback) {
+  // Only allow captures when the display configuration is not occurring.
+  scoped_refptr<CaptureData> data;
+
+  // Critical section shared with DisplaysReconfigured(...).
+  CHECK(display_configuration_capture_event_.TimedWait(
+      base::TimeDelta::FromSeconds(kDisplayReconfigurationTimeoutInSeconds)));
+  SkRegion region;
+  helper_.SwapInvalidRegion(&region);
+  VideoFrameBuffer& current_buffer = buffers_[current_buffer_];
+  current_buffer.Update();
+
+  bool flip = false;  // GL capturers need flipping.
+  if (display_create_image_func_ != NULL) {
+    // Lion requires us to use their new APIs for doing screen capture.
+    CgBlitPostLion(current_buffer, region);
+  } else if (cgl_context_) {
+    flip = true;
+    if (pixel_buffer_object_.get() != 0) {
+      GlBlitFast(current_buffer, region);
+    } else {
+      // See comment in scoped_pixel_buffer_object::Init about why the slow
+      // path is always used on 10.5.
+      GlBlitSlow(current_buffer);
+    }
+  } else {
+    CgBlitPreLion(current_buffer, region);
+  }
+
+  DataPlanes planes;
+  planes.data[0] = current_buffer.ptr();
+  planes.strides[0] = current_buffer.bytes_per_row();
+  if (flip) {
+    planes.strides[0] = -planes.strides[0];
+    planes.data[0] +=
+        (current_buffer.size().height() - 1) * current_buffer.bytes_per_row();
+  }
+
+  data = new CaptureData(planes, current_buffer.size(), pixel_format());
+  data->mutable_dirty_region() = region;
+
+  current_buffer_ = (current_buffer_ + 1) % kNumBuffers;
+  helper_.set_size_most_recent(data->size());
+  display_configuration_capture_event_.Signal();
+
+  CaptureCursor();
+
+  callback.Run(data);
+}
+
+void VideoFrameCapturerMac::CaptureCursor() {
+  if (cursor_shape_changed_callback_.is_null()) {
+    return;
+    }
+
+  NSCursor* cursor = [NSCursor currentSystemCursor];
+  if (cursor == nil) {
+    return;
+  }
+
+  NSImage* nsimage = [cursor image];
+  NSPoint hotspot = [cursor hotSpot];
+  NSSize size = [nsimage size];
+  CGImageRef image = [nsimage CGImageForProposedRect:NULL
+                                             context:nil
+                                               hints:nil];
+  if (image == nil) {
+    return;
+  }
+
+  if (CGImageGetBitsPerPixel(image) != 32 ||
+      CGImageGetBytesPerRow(image) != (size.width * 4) ||
+      CGImageGetBitsPerComponent(image) != 8) {
+    return;
+  }
+
+  // Compare the current cursor with the last one we sent to the client
+  // and exit if the cursor is the same.
+  if (current_cursor_.get() != NULL) {
+    CGImageRef current = current_cursor_.get();
+    if (CGImageGetWidth(image) == CGImageGetWidth(current) &&
+        CGImageGetHeight(image) == CGImageGetHeight(current) &&
+        CGImageGetBitsPerPixel(image) == CGImageGetBitsPerPixel(current) &&
+        CGImageGetBytesPerRow(image) == CGImageGetBytesPerRow(current) &&
+        CGImageGetBitsPerComponent(image) ==
+            CGImageGetBitsPerComponent(current)) {
+      CGDataProviderRef provider_new = CGImageGetDataProvider(image);
+      base::mac::ScopedCFTypeRef<CFDataRef> data_ref_new(
+          CGDataProviderCopyData(provider_new));
+      CGDataProviderRef provider_current = CGImageGetDataProvider(current);
+      base::mac::ScopedCFTypeRef<CFDataRef> data_ref_current(
+          CGDataProviderCopyData(provider_current));
+
+      if (data_ref_new.get() != NULL && data_ref_current.get() != NULL) {
+        int data_size = CFDataGetLength(data_ref_new);
+        CHECK(data_size == CFDataGetLength(data_ref_current));
+        const uint8* data_new = CFDataGetBytePtr(data_ref_new);
+        const uint8* data_current = CFDataGetBytePtr(data_ref_current);
+        if (memcmp(data_new, data_current, data_size) == 0) {
+          return;
+        }
+      }
+    }
+  }
+
+  VLOG(3) << "Sending cursor: " << size.width << "x" << size.height;
+
+  CGDataProviderRef provider = CGImageGetDataProvider(image);
+  base::mac::ScopedCFTypeRef<CFDataRef> image_data_ref(
+      CGDataProviderCopyData(provider));
+  if (image_data_ref.get() == NULL) {
+    return;
+  }
+  const uint8* cursor_src_data = CFDataGetBytePtr(image_data_ref);
+  int data_size = CFDataGetLength(image_data_ref);
+
+  // Create a CursorShapeInfo proto that describes the cursor and pass it to
+  // the client.
+  scoped_ptr<protocol::CursorShapeInfo> cursor_proto(
+      new protocol::CursorShapeInfo());
+  cursor_proto->mutable_data()->resize(data_size);
+  uint8* cursor_tgt_data = const_cast<uint8*>(reinterpret_cast<const uint8*>(
+      cursor_proto->mutable_data()->data()));
+
+  memcpy(cursor_tgt_data, cursor_src_data, data_size);
+
+  cursor_proto->set_width(size.width);
+  cursor_proto->set_height(size.height);
+  cursor_proto->set_hotspot_x(hotspot.x);
+  cursor_proto->set_hotspot_y(hotspot.y);
+  cursor_shape_changed_callback_.Run(cursor_proto.Pass());
+
+  // Record the last cursor image that we sent.
+  current_cursor_.reset(CGImageCreateCopy(image));
+}
+
+void VideoFrameCapturerMac::GlBlitFast(const VideoFrameBuffer& buffer,
+                                       const SkRegion& region) {
+  const int buffer_height = buffer.size().height();
+  const int buffer_width = buffer.size().width();
+
+  // Clip to the size of our current screen.
+  SkIRect clip_rect = SkIRect::MakeWH(buffer_width, buffer_height);
+  if (last_buffer_) {
+    // We are doing double buffer for the capture data so we just need to copy
+    // the invalid region from the previous capture in the current buffer.
+    // TODO(hclam): We can reduce the amount of copying here by subtracting
+    // |capturer_helper_|s region from |last_invalid_region_|.
+    // http://crbug.com/92354
+
+    // Since the image obtained from OpenGL is upside-down, need to do some
+    // magic here to copy the correct rectangle.
+    const int y_offset = (buffer_height - 1) * buffer.bytes_per_row();
+    for(SkRegion::Iterator i(last_invalid_region_); !i.done(); i.next()) {
+      SkIRect copy_rect = i.rect();
+      if (copy_rect.intersect(clip_rect)) {
+        CopyRect(last_buffer_ + y_offset,
+                 -buffer.bytes_per_row(),
+                 buffer.ptr() + y_offset,
+                 -buffer.bytes_per_row(),
+                 4,  // Bytes for pixel for RGBA.
+                 copy_rect);
+      }
+    }
+  }
+  last_buffer_ = buffer.ptr();
+  last_invalid_region_ = region;
+
+  CGLContextObj CGL_MACRO_CONTEXT = cgl_context_;
+  glBindBufferARB(GL_PIXEL_PACK_BUFFER_ARB, pixel_buffer_object_.get());
+  glReadPixels(0, 0, buffer_width, buffer_height, GL_BGRA, GL_UNSIGNED_BYTE, 0);
+  GLubyte* ptr = static_cast<GLubyte*>(
+      glMapBufferARB(GL_PIXEL_PACK_BUFFER_ARB, GL_READ_ONLY_ARB));
+  if (ptr == NULL) {
+    // If the buffer can't be mapped, assume that it's no longer valid and
+    // release it.
+    pixel_buffer_object_.Release();
+  } else {
+    // Copy only from the dirty rects. Since the image obtained from OpenGL is
+    // upside-down we need to do some magic here to copy the correct rectangle.
+    const int y_offset = (buffer_height - 1) * buffer.bytes_per_row();
+    for(SkRegion::Iterator i(region); !i.done(); i.next()) {
+      SkIRect copy_rect = i.rect();
+      if (copy_rect.intersect(clip_rect)) {
+        CopyRect(ptr + y_offset,
+           -buffer.bytes_per_row(),
+           buffer.ptr() + y_offset,
+           -buffer.bytes_per_row(),
+           4,  // Bytes for pixel for RGBA.
+           copy_rect);
+      }
+    }
+  }
+  if (!glUnmapBufferARB(GL_PIXEL_PACK_BUFFER_ARB)) {
+    // If glUnmapBuffer returns false, then the contents of the data store are
+    // undefined. This might be because the screen mode has changed, in which
+    // case it will be recreated in ScreenConfigurationChanged, but releasing
+    // the object here is the best option. Capturing will fall back on
+    // GlBlitSlow until such time as the pixel buffer object is recreated.
+    pixel_buffer_object_.Release();
+  }
+  glBindBufferARB(GL_PIXEL_PACK_BUFFER_ARB, 0);
+}
+
+void VideoFrameCapturerMac::GlBlitSlow(const VideoFrameBuffer& buffer) {
+  CGLContextObj CGL_MACRO_CONTEXT = cgl_context_;
+  glReadBuffer(GL_FRONT);
+  glPushClientAttrib(GL_CLIENT_PIXEL_STORE_BIT);
+  glPixelStorei(GL_PACK_ALIGNMENT, 4);  // Force 4-byte alignment.
+  glPixelStorei(GL_PACK_ROW_LENGTH, 0);
+  glPixelStorei(GL_PACK_SKIP_ROWS, 0);
+  glPixelStorei(GL_PACK_SKIP_PIXELS, 0);
+  // Read a block of pixels from the frame buffer.
+  glReadPixels(0, 0, buffer.size().width(), buffer.size().height(),
+               GL_BGRA, GL_UNSIGNED_BYTE, buffer.ptr());
+  glPopClientAttrib();
+}
+
+void VideoFrameCapturerMac::CgBlitPreLion(const VideoFrameBuffer& buffer,
+                                          const SkRegion& region) {
+  const int buffer_height = buffer.size().height();
+  const int buffer_width = buffer.size().width();
+
+    // Clip to the size of our current screen.
+  SkIRect clip_rect = SkIRect::MakeWH(buffer_width, buffer_height);
+
+  if (last_buffer_)
+    memcpy(buffer.ptr(), last_buffer_, buffer.bytes_per_row() * buffer_height);
+  last_buffer_ = buffer.ptr();
+  CGDirectDisplayID main_display = CGMainDisplayID();
+  uint8* display_base_address =
+      reinterpret_cast<uint8*>(CGDisplayBaseAddress(main_display));
+  int src_bytes_per_row = CGDisplayBytesPerRow(main_display);
+  int src_bytes_per_pixel = CGDisplayBitsPerPixel(main_display) / 8;
+  // TODO(hclam): We can reduce the amount of copying here by subtracting
+  // |capturer_helper_|s region from |last_invalid_region_|.
+  // http://crbug.com/92354
+  for(SkRegion::Iterator i(region); !i.done(); i.next()) {
+    SkIRect copy_rect = i.rect();
+    if (copy_rect.intersect(clip_rect)) {
+      CopyRect(display_base_address,
+               src_bytes_per_row,
+               buffer.ptr(),
+               buffer.bytes_per_row(),
+               src_bytes_per_pixel,
+               copy_rect);
+    }
+  }
+}
+
+void VideoFrameCapturerMac::CgBlitPostLion(const VideoFrameBuffer& buffer,
+                                           const SkRegion& region) {
+  const int buffer_height = buffer.size().height();
+  const int buffer_width = buffer.size().width();
+
+  // Clip to the size of our current screen.
+  SkIRect clip_rect = SkIRect::MakeWH(buffer_width, buffer_height);
+
+  if (last_buffer_)
+    memcpy(buffer.ptr(), last_buffer_, buffer.bytes_per_row() * buffer_height);
+  last_buffer_ = buffer.ptr();
+  CGDirectDisplayID display = CGMainDisplayID();
+  base::mac::ScopedCFTypeRef<CGImageRef> image(
+      display_create_image_func_(display));
+  if (image.get() == NULL)
+    return;
+  CGDataProviderRef provider = CGImageGetDataProvider(image);
+  base::mac::ScopedCFTypeRef<CFDataRef> data(CGDataProviderCopyData(provider));
+  if (data.get() == NULL)
+    return;
+  const uint8* display_base_address = CFDataGetBytePtr(data);
+  int src_bytes_per_row = CGImageGetBytesPerRow(image);
+  int src_bytes_per_pixel = CGImageGetBitsPerPixel(image) / 8;
+  // TODO(hclam): We can reduce the amount of copying here by subtracting
+  // |capturer_helper_|s region from |last_invalid_region_|.
+  // http://crbug.com/92354
+  for(SkRegion::Iterator i(region); !i.done(); i.next()) {
+    SkIRect copy_rect = i.rect();
+    if (copy_rect.intersect(clip_rect)) {
+      CopyRect(display_base_address,
+               src_bytes_per_row,
+               buffer.ptr(),
+               buffer.bytes_per_row(),
+               src_bytes_per_pixel,
+               copy_rect);
+    }
+  }
+}
+
+const SkISize& VideoFrameCapturerMac::size_most_recent() const {
+  return helper_.size_most_recent();
+}
+
+void VideoFrameCapturerMac::ScreenRefresh(CGRectCount count,
+                                          const CGRect* rect_array) {
+  SkIRect skirect_array[count];
+  for (CGRectCount i = 0; i < count; ++i) {
+    skirect_array[i] = CGRectToSkIRect(rect_array[i]);
+  }
+  SkRegion region;
+  region.setRects(skirect_array, count);
+  InvalidateRegion(region);
+}
+
+void VideoFrameCapturerMac::ScreenUpdateMove(CGScreenUpdateMoveDelta delta,
+                                             size_t count,
+                                             const CGRect* rect_array) {
+  SkIRect skirect_new_array[count];
+  for (CGRectCount i = 0; i < count; ++i) {
+    CGRect rect = rect_array[i];
+    rect = CGRectOffset(rect, delta.dX, delta.dY);
+    skirect_new_array[i] = CGRectToSkIRect(rect);
+  }
+  SkRegion region;
+  region.setRects(skirect_new_array, count);
+  InvalidateRegion(region);
+}
+
+void VideoFrameCapturerMac::DisplaysReconfigured(
+    CGDirectDisplayID display,
+    CGDisplayChangeSummaryFlags flags) {
+  if (display == CGMainDisplayID()) {
+    if (flags & kCGDisplayBeginConfigurationFlag) {
+      // Wait on |display_configuration_capture_event_| to prevent more
+      // captures from occurring on a different thread while the displays
+      // are being reconfigured.
+      CHECK(display_configuration_capture_event_.TimedWait(
+                base::TimeDelta::FromSeconds(
+                    kDisplayReconfigurationTimeoutInSeconds)));
+    } else {
+      ScreenConfigurationChanged();
+      // Now that the configuration has changed, signal the event.
+      display_configuration_capture_event_.Signal();
+    }
+  }
+}
+
+void VideoFrameCapturerMac::ScreenRefreshCallback(CGRectCount count,
+                                                  const CGRect* rect_array,
+                                                  void* user_parameter) {
+  VideoFrameCapturerMac* capturer = reinterpret_cast<VideoFrameCapturerMac*>(
+      user_parameter);
+  capturer->ScreenRefresh(count, rect_array);
+}
+
+void VideoFrameCapturerMac::ScreenUpdateMoveCallback(
+    CGScreenUpdateMoveDelta delta,
+    size_t count,
+    const CGRect* rect_array,
+    void* user_parameter) {
+  VideoFrameCapturerMac* capturer = reinterpret_cast<VideoFrameCapturerMac*>(
+      user_parameter);
+  capturer->ScreenUpdateMove(delta, count, rect_array);
+}
+
+void VideoFrameCapturerMac::DisplaysReconfiguredCallback(
+    CGDirectDisplayID display,
+    CGDisplayChangeSummaryFlags flags,
+    void* user_parameter) {
+  VideoFrameCapturerMac* capturer = reinterpret_cast<VideoFrameCapturerMac*>(
+      user_parameter);
+  capturer->DisplaysReconfigured(display, flags);
+}
+
+}  // namespace
+
+// static
+VideoFrameCapturer* VideoFrameCapturer::Create() {
+  VideoFrameCapturerMac* capturer = new VideoFrameCapturerMac();
+  if (!capturer->Init()) {
+    delete capturer;
+    capturer = NULL;
+  }
+  return capturer;
+}
+
+}  // namespace remoting