Split FakeVideoCaptureDevice into classes with single responsibility

media/capture/video/fake_video_capture_device.cc

Index: media/capture/video/fake_video_capture_device.cc
diff --git a/media/capture/video/fake_video_capture_device.cc b/media/capture/video/fake_video_capture_device.cc
index 4aa961cc42c4f94e6d4090d3a0a5d1ea1bac5931..db71c6c9e863360b9f25030eb636b87ecda5f1f8 100644
--- a/media/capture/video/fake_video_capture_device.cc
+++ b/media/capture/video/fake_video_capture_device.cc
@@ -8,11 +8,16 @@
 #include <algorithm>
 #include <utility>
 
+#include "base/atomicops.h"
 #include "base/bind.h"
 #include "base/location.h"
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/stringprintf.h"
+#include "base/threading/thread_checker.h"
 #include "base/threading/thread_task_runner_handle.h"
+#include "base/time/time.h"
 #include "media/audio/fake_audio_input_stream.h"
 #include "media/base/video_frame.h"
 #include "third_party/skia/include/core/SkBitmap.h"
@@ -23,6 +28,7 @@
 
 namespace media {
 
+namespace {
 // Sweep at 600 deg/sec.
 static const float kPacmanAngularVelocity = 600;
 // Beep every 500 ms.
@@ -33,18 +39,264 @@ static const float kGradientFrequency = 1.f / 5;
 static const double kMinZoom = 100.0;
 static const double kMaxZoom = 400.0;
 static const double kZoomStep = 1.0;
+static const double kInitialZoom = 100.0;
+
+static const gfx::Size kSupportedSizes[] = {
+    gfx::Size(96, 96), gfx::Size(320, 240), gfx::Size(640, 480),
+    gfx::Size(1280, 720), gfx::Size(1920, 1080)};
+static const int kSupportedSizesCount =
+    sizeof(kSupportedSizes) / sizeof(gfx::Size);
+
+static const VideoPixelFormat kSupportedPixelFormats[] = {
+    PIXEL_FORMAT_I420, PIXEL_FORMAT_Y16, PIXEL_FORMAT_ARGB};
+
+static gfx::Size SnapToSupportedSize(const gfx::Size& requested_size) {
+  for (int i = 0; i < kSupportedSizesCount; i++) {
+    const gfx::Size& supported_size = kSupportedSizes[i];
+    if (requested_size.width() <= supported_size.width()) {
+      return supported_size;
+    }

[mcasas, 2017/02/15 00:44:19]

No {} in one-line bodies.

[chfremer, 2017/02/15 18:11:29]

Done.

+  }

[mcasas, 2017/02/15 00:44:19]

for (const gfx::Size& supported_size : kSupportedSizes) {
  if (requested_size.width() <= supported_size.width())
    return supported_size;

}
return arraysize(kSupportedSizes) - 1;

(Not super sure if the last line will work though).

Also, note that this algorithm implicitly relies on
|kSupportedSizes| being ordered increasingly, from 
small to large sizes.  Please add a comment at such
effect.

[chfremer, 2017/02/15 18:11:29]

Done.

+  return kSupportedSizes[kSupportedSizesCount - 1];
+}
+
+class FakeVideoCaptureDevice;

[mcasas, 2017/02/15 00:44:19]

Probably not needed? I don't see any refs to it
before its definition in l.185

[chfremer, 2017/02/15 18:11:29]

Done.

+
+// Represents the current state of a FakeVideoCaptureDevice.
+// This is a separate struct because read-access to it is shared with several
+// collaborating classes.
+struct FakeDeviceState {
+  FakeDeviceState(float zoom, float frame_rate, VideoPixelFormat pixel_format)
+      : zoom(zoom),
+        format(gfx::Size(), frame_rate, pixel_format, PIXEL_STORAGE_CPU) {}
+
+  uint32_t zoom;
+  VideoCaptureFormat format;
+};
+
+// Paints a frame into the given |target_buffer|.
+class FramePainter {
+ public:
+  virtual void PaintFrame(base::TimeDelta elapsed_time,
+                          uint8_t* target_buffer) = 0;
+};

[mcasas, 2017/02/15 00:44:19]

Why a base class if there's only one class
deriving from it?

[chfremer, 2017/02/15 18:11:29]

Short answer: For abstraction and loose coupling.

Slightly more elaborate answer: Users of FramePainter (i.e. classes
FakePhotoDevice and FakeVideoCaptureDevice) do not need to know what
implementation is being used. They should work the same with any FramePainter
(including Mocks). Depending on the abstraction instead of a concrete
implementation makes them testable and reusable without PacmanFramePainter (or
any of its dependencies). Also, human readers do not have to read
PacmanFramePainter (or any of its dependencies) in order to understand what
FakePhotoDevice and FakeVideoCaptureDevice do.

[mcasas, 2017/02/15 18:23:47]

That's all good, but in Chromium we only abstract things
when we need to. IIUC PacmanFramePainter is only
used in this file, and it's the only implementation of
FramePainter, so there's no need to hide behind 
abstractions.  If you would have 2 implementations of
FramePainter, I'd go with your rationale, but otherwise
I think it's more complication than worth. Please remove
it.

[chfremer, 2017/02/15 18:37:16]

Done.

+
+// Paints a "pacman-like" animated circle including textual information such
+// as a frame count and timer.
+class PacmanFramePainter : public FramePainter {
+ public:
+  // Currently, only the following values are supported for |pixel_format|:
+  //   PIXEL_FORMAT_I420
+  //   PIXEL_FORMAT_Y16
+  //   PIXEL_FORMAT_ARGB
+  PacmanFramePainter(VideoPixelFormat pixel_format,
+                     const FakeDeviceState* fake_device_state);
+
+  // Implementation of FramePainter
+  void PaintFrame(base::TimeDelta elapsed_time,
+                  uint8_t* target_buffer) override;
+
+ private:
+  void DrawGradientSquares(base::TimeDelta elapsed_time,
+                           uint8_t* target_buffer);
+
+  void DrawPacman(base::TimeDelta elapsed_time, uint8_t* target_buffer);
+
+  const VideoPixelFormat pixel_format_;
+  const FakeDeviceState* fake_device_state_ = nullptr;
+};
+
+// Delivers frames to a client, which is set via Initialize().
+class FrameDeliveryStrategy {
+ public:
+  virtual ~FrameDeliveryStrategy() {}
+  virtual void Initialize(VideoPixelFormat pixel_format,
+                          std::unique_ptr<VideoCaptureDevice::Client> client,
+                          const FakeDeviceState* device_state) = 0;
+  virtual void Uninitialize() = 0;
+  virtual uint8_t* PrepareBufferForNextFrame() = 0;
+  virtual void DeliverFrame() = 0;
+
+ protected:
+  const FakeDeviceState* device_state_ = nullptr;
+  std::unique_ptr<VideoCaptureDevice::Client> client_;
+  // The system time when we receive the first frame.
+  base::TimeTicks first_ref_time_;
+};
+
+// Delivers frames using its own buffers via OnIncomingCapturedData().
+class OwnBufferFrameDeliveryStrategy : public FrameDeliveryStrategy {
+ public:
+  OwnBufferFrameDeliveryStrategy();
+  ~OwnBufferFrameDeliveryStrategy() override;
+
+  // Implementation of FrameDeliveryStrategy
+  void Initialize(VideoPixelFormat pixel_format,
+                  std::unique_ptr<VideoCaptureDevice::Client> client,
+                  const FakeDeviceState* device_state) override;
+  void Uninitialize() override;
+  uint8_t* PrepareBufferForNextFrame() override;
+  void DeliverFrame() override;
+
+ private:
+  std::unique_ptr<uint8_t[]> buffer_;
+};
+
+// Delivers frames using buffers provided by the client via
+// OnIncomingCapturedBuffer().
+class ClientBufferFrameDeliveryStrategy : public FrameDeliveryStrategy {
+ public:
+  ClientBufferFrameDeliveryStrategy();
+  ~ClientBufferFrameDeliveryStrategy() override;
+
+  // Implementation of FrameDeliveryStrategy
+  void Initialize(VideoPixelFormat pixel_format,
+                  std::unique_ptr<VideoCaptureDevice::Client> client,
+                  const FakeDeviceState* device_state) override;
+  void Uninitialize() override;
+  uint8_t* PrepareBufferForNextFrame() override;
+  void DeliverFrame() override;
+
+ private:
+  VideoCaptureDevice::Client::Buffer capture_buffer_;
+};
+
+// Implements the photo functionality of a VideoCaptureDevice
+class FakePhotoDevice {
+ public:
+  FakePhotoDevice(std::unique_ptr<FramePainter> argb_painter,
+                  const FakeDeviceState* fake_device_state);
+  ~FakePhotoDevice();
+
+  void GetPhotoCapabilities(
+      VideoCaptureDevice::GetPhotoCapabilitiesCallback callback);
+  void TakePhoto(VideoCaptureDevice::TakePhotoCallback callback,
+                 base::TimeDelta elapsed_time);
+
+ private:
+  const std::unique_ptr<FramePainter> argb_painter_;
+  const FakeDeviceState* const fake_device_state_;
+};
+
+// Implementation of VideoCaptureDevice that generates test frames. This is
+// useful for testing the video capture components without having to use real
+// devices. The implementation schedules delayed tasks to itself to generate and
+// deliver frames at the requested rate.
+class FakeVideoCaptureDevice : public VideoCaptureDevice {
+ public:
+  FakeVideoCaptureDevice(
+      std::unique_ptr<FramePainter> frame_painter,
+      std::unique_ptr<FrameDeliveryStrategy> frame_delivery_strategy,
+      std::unique_ptr<FakePhotoDevice> photo_device,
+      std::unique_ptr<FakeDeviceState> device_state);
+  ~FakeVideoCaptureDevice() override;
+
+  // VideoCaptureDevice implementation.
+  void AllocateAndStart(const VideoCaptureParams& params,
+                        std::unique_ptr<Client> client) override;
+  void StopAndDeAllocate() override;
+  void GetPhotoCapabilities(GetPhotoCapabilitiesCallback callback) override;
+  void SetPhotoOptions(mojom::PhotoSettingsPtr settings,
+                       SetPhotoOptionsCallback callback) override;
+  void TakePhoto(TakePhotoCallback callback) override;
+
+ private:
+  void BeepAndScheduleNextCapture(base::TimeTicks expected_execution_time);
+  void OnNextFrameDue(base::TimeTicks expected_execution_time, int session_id);
+
+  const std::unique_ptr<FramePainter> frame_painter_;
+  const std::unique_ptr<FrameDeliveryStrategy> frame_delivery_strategy_;
+  const std::unique_ptr<FakePhotoDevice> photo_device_;
+  const std::unique_ptr<FakeDeviceState> device_state_;
+  int current_session_id_ = 0;
+
+  // Time when the next beep occurs.
+  base::TimeDelta beep_time_;
+  // Time since the fake video started rendering frames.
+  base::TimeDelta elapsed_time_;
+
+  base::ThreadChecker thread_checker_;
+
+  // FakeVideoCaptureDevice post tasks to itself for frame construction and
+  // needs to deal with asynchronous StopAndDeallocate().
+  base::WeakPtrFactory<FakeVideoCaptureDevice> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(FakeVideoCaptureDevice);
+};
+
+}  // anonymous namespace
+
+// static
+void FakeVideoCaptureDeviceMaker::GetSupportedSizes(
+    std::vector<gfx::Size>* supported_sizes) {
+  for (int i = 0; i < kSupportedSizesCount; i++)
+    supported_sizes->push_back(kSupportedSizes[i]);
+}
+
+// static
+std::unique_ptr<VideoCaptureDevice> FakeVideoCaptureDeviceMaker::MakeInstance(
+    VideoPixelFormat pixel_format,
+    DeliveryMode delivery_mode,
+    float frame_rate) {
+  bool pixel_format_supported = false;
+  for (const auto& supported_pixel_format : kSupportedPixelFormats) {
+    if (pixel_format == supported_pixel_format) {
+      pixel_format_supported = true;
+      break;
+    }
+  }
+  if (!pixel_format_supported) {
+    DLOG(ERROR) << "Requested an unsupported pixel format "
+                << VideoPixelFormatToString(pixel_format);
+    return nullptr;
+  }
+
+  auto device_state =
+      base::MakeUnique<FakeDeviceState>(kInitialZoom, frame_rate, pixel_format);
+  auto video_frame_painter =
+      base::MakeUnique<PacmanFramePainter>(pixel_format, device_state.get());
+  std::unique_ptr<FrameDeliveryStrategy> frame_delivery_strategy;
+  switch (delivery_mode) {
+    case DeliveryMode::USE_OWN_BUFFERS:
+      frame_delivery_strategy =
+          base::MakeUnique<OwnBufferFrameDeliveryStrategy>();
+      break;
+    case DeliveryMode::USE_CLIENT_BUFFERS:
+      frame_delivery_strategy =
+          base::MakeUnique<ClientBufferFrameDeliveryStrategy>();
+      break;
+  }
+
+  auto photo_frame_painter = base::MakeUnique<PacmanFramePainter>(
+      PIXEL_FORMAT_ARGB, device_state.get());
+  auto photo_device = base::MakeUnique<FakePhotoDevice>(
+      std::move(photo_frame_painter), device_state.get());
+
+  return base::MakeUnique<FakeVideoCaptureDevice>(
+      std::move(video_frame_painter), std::move(frame_delivery_strategy),
+      std::move(photo_device), std::move(device_state));
+}
+
+PacmanFramePainter::PacmanFramePainter(VideoPixelFormat pixel_format,
+                                       const FakeDeviceState* fake_device_state)
+    : pixel_format_(pixel_format), fake_device_state_(fake_device_state) {}
+
+void PacmanFramePainter::PaintFrame(base::TimeDelta elapsed_time,
+                                    uint8_t* target_buffer) {
+  DrawPacman(elapsed_time, target_buffer);
+  DrawGradientSquares(elapsed_time, target_buffer);
+}
 
 // Starting from top left, -45 deg gradient.  Value at point (row, column) is
 // calculated as (top_left_value + (row + column) * step) % MAX_VALUE, where
 // step is MAX_VALUE / (width + height).  MAX_VALUE is 255 (for 8 bit per
 // component) or 65535 for Y16.
 // This is handy for pixel tests where we use the squares to verify rendering.
-void DrawGradientSquares(VideoPixelFormat frame_format,
-                         uint8_t* const pixels,
-                         base::TimeDelta elapsed_time,
-                         const gfx::Size& frame_size) {
-  const int width = frame_size.width();
-  const int height = frame_size.height();
+void PacmanFramePainter::DrawGradientSquares(base::TimeDelta elapsed_time,
+                                             uint8_t* target_buffer) {
+  const int width = fake_device_state_->format.frame_size.width();
+  const int height = fake_device_state_->format.frame_size.height();
+
   const int side = width / 16;  // square side length.
   DCHECK(side);
   const gfx::Point squares[] = {{0, 0},
@@ -60,18 +312,18 @@ void DrawGradientSquares(VideoPixelFormat frame_format,
         const unsigned int value =
             static_cast<unsigned int>(start + (x + y) * color_step) & 0xFFFF;
         size_t offset = (y * width) + x;
-        switch (frame_format) {
+        switch (pixel_format_) {
           case PIXEL_FORMAT_Y16:
-            pixels[offset * sizeof(uint16_t)] = value & 0xFF;
-            pixels[offset * sizeof(uint16_t) + 1] = value >> 8;
+            target_buffer[offset * sizeof(uint16_t)] = value & 0xFF;
+            target_buffer[offset * sizeof(uint16_t) + 1] = value >> 8;
             break;
           case PIXEL_FORMAT_ARGB:
-            pixels[offset * sizeof(uint32_t) + 1] = value >> 8;
-            pixels[offset * sizeof(uint32_t) + 2] = value >> 8;
-            pixels[offset * sizeof(uint32_t) + 3] = value >> 8;
+            target_buffer[offset * sizeof(uint32_t) + 1] = value >> 8;
+            target_buffer[offset * sizeof(uint32_t) + 2] = value >> 8;
+            target_buffer[offset * sizeof(uint32_t) + 3] = value >> 8;
             break;
           default:
-            pixels[offset] = value >> 8;
+            target_buffer[offset] = value >> 8;
             break;
         }
       }
@@ -79,37 +331,34 @@ void DrawGradientSquares(VideoPixelFormat frame_format,
   }
 }
 
-void DrawPacman(VideoPixelFormat frame_format,
-                uint8_t* const data,
-                base::TimeDelta elapsed_time,
-                float frame_rate,
-                const gfx::Size& frame_size,
-                double zoom) {
+void PacmanFramePainter::DrawPacman(base::TimeDelta elapsed_time,
+                                    uint8_t* target_buffer) {
+  const int width = fake_device_state_->format.frame_size.width();
+  const int height = fake_device_state_->format.frame_size.height();
+
   // |kN32_SkColorType| stands for the appropriate RGBA/BGRA format.
-  const SkColorType colorspace = (frame_format == PIXEL_FORMAT_ARGB)
+  const SkColorType colorspace = (pixel_format_ == PIXEL_FORMAT_ARGB)
                                      ? kN32_SkColorType
                                      : kAlpha_8_SkColorType;
   // Skia doesn't support 16 bit alpha rendering, so we 8 bit alpha and then use
   // this as high byte values in 16 bit pixels.
-  const SkImageInfo info = SkImageInfo::Make(
-      frame_size.width(), frame_size.height(), colorspace, kOpaque_SkAlphaType);
+  const SkImageInfo info =
+      SkImageInfo::Make(width, height, colorspace, kOpaque_SkAlphaType);
   SkBitmap bitmap;
   bitmap.setInfo(info);
-  bitmap.setPixels(data);
+  bitmap.setPixels(target_buffer);
   SkPaint paint;
   paint.setStyle(SkPaint::kFill_Style);
   SkCanvas canvas(bitmap);
 
-  const SkScalar unscaled_zoom = zoom / 100.f;
+  const SkScalar unscaled_zoom = fake_device_state_->zoom / 100.f;
   SkMatrix matrix;
-  matrix.setScale(unscaled_zoom, unscaled_zoom, frame_size.width() / 2,
-                  frame_size.height() / 2);
+  matrix.setScale(unscaled_zoom, unscaled_zoom, width / 2, height / 2);
   canvas.setMatrix(matrix);
 
   // Equalize Alpha_8 that has light green background while RGBA has white.
-  if (frame_format == PIXEL_FORMAT_ARGB) {
-    const SkRect full_frame =
-        SkRect::MakeWH(frame_size.width(), frame_size.height());
+  if (pixel_format_ == PIXEL_FORMAT_ARGB) {
+    const SkRect full_frame = SkRect::MakeWH(width, height);
     paint.setARGB(255, 0, 127, 0);
     canvas.drawRect(full_frame, paint);
   }
@@ -118,9 +367,8 @@ void DrawPacman(VideoPixelFormat frame_format,
   // Draw a sweeping circle to show an animation.
   const float end_angle =
       fmod(kPacmanAngularVelocity * elapsed_time.InSecondsF(), 361);
-  const int radius = std::min(frame_size.width(), frame_size.height()) / 4;
-  const SkRect rect = SkRect::MakeXYWH(frame_size.width() / 2 - radius,
-                                       frame_size.height() / 2 - radius,
+  const int radius = std::min(width, height) / 4;
+  const SkRect rect = SkRect::MakeXYWH(width / 2 - radius, height / 2 - radius,
                                        2 * radius, 2 * radius);
   canvas.drawArc(rect, 0, end_angle, true, paint);
 
@@ -129,7 +377,8 @@ void DrawPacman(VideoPixelFormat frame_format,
   const int seconds = elapsed_time.InSeconds() % 60;
   const int minutes = elapsed_time.InMinutes() % 60;
   const int hours = elapsed_time.InHours();
-  const int frame_count = elapsed_time.InMilliseconds() * frame_rate / 1000;
+  const int frame_count = elapsed_time.InMilliseconds() *
+                          fake_device_state_->format.frame_rate / 1000;
 
   const std::string time_string =
       base::StringPrintf("%d:%02d:%02d:%03d %d", hours, minutes, seconds,
@@ -137,46 +386,49 @@ void DrawPacman(VideoPixelFormat frame_format,
   canvas.scale(3, 3);
   canvas.drawText(time_string.data(), time_string.length(), 30, 20, paint);
 
-  if (frame_format == PIXEL_FORMAT_Y16) {
+  if (pixel_format_ == PIXEL_FORMAT_Y16) {
     // Use 8 bit bitmap rendered to first half of the buffer as high byte values
     // for the whole buffer. Low byte values are not important.
-    for (int i = frame_size.GetArea() - 1; i >= 0; --i)
-      data[i * 2 + 1] = data[i];
+    for (int i = (width * height) - 1; i >= 0; --i)
+      target_buffer[i * 2 + 1] = target_buffer[i];
   }
-  DrawGradientSquares(frame_format, data, elapsed_time, frame_size);
 }
 
-// Creates a PNG-encoded frame and sends it back to |callback|. The other
-// parameters are used to replicate the PacMan rendering.
-void DoTakeFakePhoto(VideoCaptureDevice::TakePhotoCallback callback,
-                     const VideoCaptureFormat& capture_format,
-                     base::TimeDelta elapsed_time,
-                     float fake_capture_rate,
-                     uint32_t zoom) {
-  std::unique_ptr<uint8_t[]> buffer(new uint8_t[VideoFrame::AllocationSize(
-      PIXEL_FORMAT_ARGB, capture_format.frame_size)]);
+FakePhotoDevice::FakePhotoDevice(std::unique_ptr<FramePainter> argb_painter,
+                                 const FakeDeviceState* fake_device_state)
+    : argb_painter_(std::move(argb_painter)),
+      fake_device_state_(fake_device_state) {}
 
-  DrawPacman(PIXEL_FORMAT_ARGB, buffer.get(), elapsed_time, fake_capture_rate,
-             capture_format.frame_size, zoom);
+FakePhotoDevice::~FakePhotoDevice() = default;
 
+void FakePhotoDevice::TakePhoto(VideoCaptureDevice::TakePhotoCallback callback,
+                                base::TimeDelta elapsed_time) {
+  // Create a PNG-encoded frame and send it back to |callback|.
+  std::unique_ptr<uint8_t[]> buffer(new uint8_t[VideoFrame::AllocationSize(
+      PIXEL_FORMAT_ARGB, fake_device_state_->format.frame_size)]);
+  argb_painter_->PaintFrame(elapsed_time, buffer.get());
   mojom::BlobPtr blob = mojom::Blob::New();
-  const bool result = gfx::PNGCodec::Encode(
-      buffer.get(), gfx::PNGCodec::FORMAT_RGBA, capture_format.frame_size,
-      capture_format.frame_size.width() * 4, true /* discard_transparency */,
-      std::vector<gfx::PNGCodec::Comment>(), &blob->data);
+  const bool result =
+      gfx::PNGCodec::Encode(buffer.get(), gfx::PNGCodec::FORMAT_RGBA,
+                            fake_device_state_->format.frame_size,
+                            fake_device_state_->format.frame_size.width() * 4,
+                            true /* discard_transparency */,
+                            std::vector<gfx::PNGCodec::Comment>(), &blob->data);
   DCHECK(result);
 
   blob->mime_type = "image/png";
   callback.Run(std::move(blob));
 }
 
-FakeVideoCaptureDevice::FakeVideoCaptureDevice(BufferOwnership buffer_ownership,
-                                               float fake_capture_rate,
-                                               VideoPixelFormat pixel_format)
-    : buffer_ownership_(buffer_ownership),
-      fake_capture_rate_(fake_capture_rate),
-      pixel_format_(pixel_format),
-      current_zoom_(kMinZoom),
+FakeVideoCaptureDevice::FakeVideoCaptureDevice(
+    std::unique_ptr<FramePainter> frame_painter,
+    std::unique_ptr<FrameDeliveryStrategy> frame_delivery_strategy,
+    std::unique_ptr<FakePhotoDevice> photo_device,
+    std::unique_ptr<FakeDeviceState> device_state)
+    : frame_painter_(std::move(frame_painter)),
+      frame_delivery_strategy_(std::move(frame_delivery_strategy)),
+      photo_device_(std::move(photo_device)),
+      device_state_(std::move(device_state)),
       weak_factory_(this) {}
 
 FakeVideoCaptureDevice::~FakeVideoCaptureDevice() {
@@ -188,61 +440,32 @@ void FakeVideoCaptureDevice::AllocateAndStart(
     std::unique_ptr<VideoCaptureDevice::Client> client) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
-  client_ = std::move(client);
-
-  // Incoming |params| can be none of the supported formats, so we get the
-  // closest thing rounded up. TODO(mcasas): Use the |params|, if they belong to
-  // the supported ones, when http://crbug.com/309554 is verified.
-  capture_format_.frame_rate = fake_capture_rate_;
-  if (params.requested_format.frame_size.width() > 1280)
-    capture_format_.frame_size.SetSize(1920, 1080);
-  else if (params.requested_format.frame_size.width() > 640)
-    capture_format_.frame_size.SetSize(1280, 720);
-  else if (params.requested_format.frame_size.width() > 320)
-    capture_format_.frame_size.SetSize(640, 480);
-  else if (params.requested_format.frame_size.width() > 96)
-    capture_format_.frame_size.SetSize(320, 240);
-  else
-    capture_format_.frame_size.SetSize(96, 96);
-
-  capture_format_.pixel_format = pixel_format_;
-  if (buffer_ownership_ == BufferOwnership::CLIENT_BUFFERS) {
-    capture_format_.pixel_storage = PIXEL_STORAGE_CPU;
-    capture_format_.pixel_format = PIXEL_FORMAT_ARGB;
-    DVLOG(1) << "starting with client argb buffers";
-  } else if (buffer_ownership_ == BufferOwnership::OWN_BUFFERS) {
-    capture_format_.pixel_storage = PIXEL_STORAGE_CPU;
-    DVLOG(1) << "starting with own " << VideoPixelFormatToString(pixel_format_)
-             << " buffers";
-  }
-
-  if (buffer_ownership_ == BufferOwnership::OWN_BUFFERS) {
-    fake_frame_.reset(new uint8_t[VideoFrame::AllocationSize(
-        pixel_format_, capture_format_.frame_size)]);
-  }
-
   beep_time_ = base::TimeDelta();
   elapsed_time_ = base::TimeDelta();
-
-  if (buffer_ownership_ == BufferOwnership::CLIENT_BUFFERS)
-    BeepAndScheduleNextCapture(
-        base::TimeTicks::Now(),
-        base::Bind(&FakeVideoCaptureDevice::CaptureUsingClientBuffers,
-                   weak_factory_.GetWeakPtr()));
-  else if (buffer_ownership_ == BufferOwnership::OWN_BUFFERS)
-    BeepAndScheduleNextCapture(
-        base::TimeTicks::Now(),
-        base::Bind(&FakeVideoCaptureDevice::CaptureUsingOwnBuffers,
-                   weak_factory_.GetWeakPtr()));
+  device_state_->format.frame_size =
+      SnapToSupportedSize(params.requested_format.frame_size);
+  frame_delivery_strategy_->Initialize(device_state_->format.pixel_format,
+                                       std::move(client), device_state_.get());
+  current_session_id_++;
+  BeepAndScheduleNextCapture(base::TimeTicks::Now());
 }
 
 void FakeVideoCaptureDevice::StopAndDeAllocate() {
   DCHECK(thread_checker_.CalledOnValidThread());
-  client_.reset();
+
+  // Invalidate WeakPtr to stop the perpetual scheduling of tasks.
+  weak_factory_.InvalidateWeakPtrs();
+  frame_delivery_strategy_->Uninitialize();
 }
 
 void FakeVideoCaptureDevice::GetPhotoCapabilities(
     GetPhotoCapabilitiesCallback callback) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  photo_device_->GetPhotoCapabilities(std::move(callback));
+}
+
+void FakePhotoDevice::GetPhotoCapabilities(
+    VideoCaptureDevice::GetPhotoCapabilitiesCallback callback) {
   mojom::PhotoCapabilitiesPtr photo_capabilities =
       mojom::PhotoCapabilities::New();
   photo_capabilities->iso = mojom::Range::New();
@@ -251,17 +474,19 @@ void FakeVideoCaptureDevice::GetPhotoCapabilities(
   photo_capabilities->iso->min = 100.0;
   photo_capabilities->iso->step = 0.0;
   photo_capabilities->height = mojom::Range::New();
-  photo_capabilities->height->current = capture_format_.frame_size.height();
+  photo_capabilities->height->current =
+      fake_device_state_->format.frame_size.height();
   photo_capabilities->height->max = 1080.0;
   photo_capabilities->height->min = 96.0;
   photo_capabilities->height->step = 1.0;
   photo_capabilities->width = mojom::Range::New();
-  photo_capabilities->width->current = capture_format_.frame_size.width();
+  photo_capabilities->width->current =
+      fake_device_state_->format.frame_size.width();
   photo_capabilities->width->max = 1920.0;
   photo_capabilities->width->min = 96.0;
-  photo_capabilities->width->step = 1;
+  photo_capabilities->width->step = 1.0;
   photo_capabilities->zoom = mojom::Range::New();
-  photo_capabilities->zoom->current = current_zoom_;
+  photo_capabilities->zoom->current = fake_device_state_->zoom;
   photo_capabilities->zoom->max = kMaxZoom;
   photo_capabilities->zoom->min = kMinZoom;
   photo_capabilities->zoom->step = kZoomStep;
@@ -281,80 +506,123 @@ void FakeVideoCaptureDevice::GetPhotoCapabilities(
 
 void FakeVideoCaptureDevice::SetPhotoOptions(mojom::PhotoSettingsPtr settings,
                                              SetPhotoOptionsCallback callback) {
-  if (settings->has_zoom)
-    current_zoom_ = std::max(kMinZoom, std::min(settings->zoom, kMaxZoom));
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (settings->has_zoom) {
+    device_state_->zoom =
+        std::max(kMinZoom, std::min(settings->zoom, kMaxZoom));
+  }
+
   callback.Run(true);
 }
 
 void FakeVideoCaptureDevice::TakePhoto(TakePhotoCallback callback) {
+  DCHECK(thread_checker_.CalledOnValidThread());
   base::ThreadTaskRunnerHandle::Get()->PostTask(
-      FROM_HERE,
-      base::Bind(&DoTakeFakePhoto, base::Passed(&callback), capture_format_,
-                 elapsed_time_, fake_capture_rate_, current_zoom_));
+      FROM_HERE, base::Bind(&FakePhotoDevice::TakePhoto,
+                            base::Unretained(photo_device_.get()),
+                            base::Passed(&callback), elapsed_time_));
 }
 
-void FakeVideoCaptureDevice::CaptureUsingOwnBuffers(
-    base::TimeTicks expected_execution_time) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  const size_t frame_size = capture_format_.ImageAllocationSize();
+OwnBufferFrameDeliveryStrategy::OwnBufferFrameDeliveryStrategy() = default;
+
+OwnBufferFrameDeliveryStrategy::~OwnBufferFrameDeliveryStrategy() = default;
+
+void OwnBufferFrameDeliveryStrategy::Initialize(
+    VideoPixelFormat pixel_format,
+    std::unique_ptr<VideoCaptureDevice::Client> client,
+    const FakeDeviceState* device_state) {
+  client_ = std::move(client);
+  device_state_ = device_state;
+  buffer_.reset(new uint8_t[VideoFrame::AllocationSize(
+      pixel_format, device_state_->format.frame_size)]);
+}
+
+void OwnBufferFrameDeliveryStrategy::Uninitialize() {
+  client_.reset();
+  device_state_ = nullptr;
+  buffer_.reset();
+}
+
+uint8_t* OwnBufferFrameDeliveryStrategy::PrepareBufferForNextFrame() {
+  if (client_ == nullptr)

[mcasas, 2017/02/15 00:44:19]

if (!client_)

here and in l.556

[chfremer, 2017/02/15 18:11:29]

Done.

+    return nullptr;
 
-  memset(fake_frame_.get(), 0, frame_size);
-  DrawPacman(capture_format_.pixel_format, fake_frame_.get(), elapsed_time_,
-             fake_capture_rate_, capture_format_.frame_size, current_zoom_);
-  // Give the captured frame to the client.
+  const size_t frame_size = device_state_->format.ImageAllocationSize();
+  memset(buffer_.get(), 0, frame_size);
+  return buffer_.get();
+}
+
+void OwnBufferFrameDeliveryStrategy::DeliverFrame() {
+  if (client_ == nullptr)
+    return;
+  const size_t frame_size = device_state_->format.ImageAllocationSize();
   base::TimeTicks now = base::TimeTicks::Now();
   if (first_ref_time_.is_null())
     first_ref_time_ = now;
-  client_->OnIncomingCapturedData(fake_frame_.get(), frame_size,
-                                  capture_format_, 0 /* rotation */, now,
+  client_->OnIncomingCapturedData(buffer_.get(), frame_size,
+                                  device_state_->format, 0 /* rotation */, now,
                                   now - first_ref_time_);
-  BeepAndScheduleNextCapture(
-      expected_execution_time,
-      base::Bind(&FakeVideoCaptureDevice::CaptureUsingOwnBuffers,
-                 weak_factory_.GetWeakPtr()));
 }
 
-void FakeVideoCaptureDevice::CaptureUsingClientBuffers(
-    base::TimeTicks expected_execution_time) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+ClientBufferFrameDeliveryStrategy::ClientBufferFrameDeliveryStrategy() =
+    default;
+
+ClientBufferFrameDeliveryStrategy::~ClientBufferFrameDeliveryStrategy() =
+    default;
+
+void ClientBufferFrameDeliveryStrategy::Initialize(
+    VideoPixelFormat,
+    std::unique_ptr<VideoCaptureDevice::Client> client,
+    const FakeDeviceState* device_state) {
+  client_ = std::move(client);
+  device_state_ = device_state;
+}
+
+void ClientBufferFrameDeliveryStrategy::Uninitialize() {
+  client_.reset();
+  device_state_ = nullptr;
+}
+
+uint8_t* ClientBufferFrameDeliveryStrategy::PrepareBufferForNextFrame() {
+  if (client_ == nullptr)
+    return nullptr;
 
   const int arbitrary_frame_feedback_id = 0;
-  VideoCaptureDevice::Client::Buffer capture_buffer =
-      client_->ReserveOutputBuffer(
-          capture_format_.frame_size, capture_format_.pixel_format,
-          capture_format_.pixel_storage, arbitrary_frame_feedback_id);
-  DLOG_IF(ERROR, !capture_buffer.is_valid())
+  capture_buffer_ = client_->ReserveOutputBuffer(
+      device_state_->format.frame_size, device_state_->format.pixel_format,
+      device_state_->format.pixel_storage, arbitrary_frame_feedback_id);
+  DLOG_IF(ERROR, !capture_buffer_.is_valid())
       << "Couldn't allocate Capture Buffer";
   auto buffer_access =
-      capture_buffer.handle_provider()->GetHandleForInProcessAccess();
+      capture_buffer_.handle_provider()->GetHandleForInProcessAccess();
   DCHECK(buffer_access->data()) << "Buffer has NO backing memory";
 
-  DCHECK_EQ(PIXEL_STORAGE_CPU, capture_format_.pixel_storage);
+  DCHECK_EQ(device_state_->format.pixel_storage, PIXEL_STORAGE_CPU);
+
   uint8_t* data_ptr = buffer_access->data();
   memset(data_ptr, 0, buffer_access->mapped_size());
-  DrawPacman(capture_format_.pixel_format, data_ptr, elapsed_time_,
-             fake_capture_rate_, capture_format_.frame_size, current_zoom_);
+  return data_ptr;
+}
+
+void ClientBufferFrameDeliveryStrategy::DeliverFrame() {
+  if (client_ == nullptr)
+    return;
 
-  // Give the captured frame to the client.
   base::TimeTicks now = base::TimeTicks::Now();
   if (first_ref_time_.is_null())
     first_ref_time_ = now;
-  client_->OnIncomingCapturedBuffer(std::move(capture_buffer), capture_format_,
-                                    now, now - first_ref_time_);
-
-  BeepAndScheduleNextCapture(
-      expected_execution_time,
-      base::Bind(&FakeVideoCaptureDevice::CaptureUsingClientBuffers,
-                 weak_factory_.GetWeakPtr()));
+  client_->OnIncomingCapturedBuffer(std::move(capture_buffer_),
+                                    device_state_->format, now,
+                                    now - first_ref_time_);
 }
 
 void FakeVideoCaptureDevice::BeepAndScheduleNextCapture(
-    base::TimeTicks expected_execution_time,
-    const base::Callback<void(base::TimeTicks)>& next_capture) {
+    base::TimeTicks expected_execution_time) {
+  DCHECK(thread_checker_.CalledOnValidThread());
   const base::TimeDelta beep_interval =
       base::TimeDelta::FromMilliseconds(kBeepInterval);
   const base::TimeDelta frame_interval =
-      base::TimeDelta::FromMicroseconds(1e6 / fake_capture_rate_);
+      base::TimeDelta::FromMicroseconds(1e6 / device_state_->format.frame_rate);
   beep_time_ += frame_interval;
   elapsed_time_ += frame_interval;
 
@@ -372,7 +640,24 @@ void FakeVideoCaptureDevice::BeepAndScheduleNextCapture(
       std::max(current_time, expected_execution_time + frame_interval);
   const base::TimeDelta delay = next_execution_time - current_time;
   base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
-      FROM_HERE, base::Bind(next_capture, next_execution_time), delay);
+      FROM_HERE, base::Bind(&FakeVideoCaptureDevice::OnNextFrameDue,
+                            weak_factory_.GetWeakPtr(), next_execution_time,
+                            current_session_id_),
+      delay);
+}
+
+void FakeVideoCaptureDevice::OnNextFrameDue(
+    base::TimeTicks expected_execution_time,
+    int session_id) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (session_id != current_session_id_)
+    return;
+
+  uint8_t* const buffer = frame_delivery_strategy_->PrepareBufferForNextFrame();
+  frame_painter_->PaintFrame(elapsed_time_, buffer);
+  frame_delivery_strategy_->DeliverFrame();
+
+  BeepAndScheduleNextCapture(expected_execution_time);
 }
 
 }  // namespace media