Update VideoFramePump to pass un-changed frames to encoders.

remoting/host/video_frame_pump_unittest.cc

 // Copyright 2015 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_pump.h"
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "remoting/base/auto_thread.h"
 #include "remoting/base/auto_thread_task_runner.h"
 #include "remoting/codec/video_encoder.h"
 #include "remoting/codec/video_encoder_verbatim.h"
 #include "remoting/host/desktop_capturer_proxy.h"
 #include "remoting/host/fake_desktop_capturer.h"
 #include "remoting/host/host_mock_objects.h"
 #include "remoting/proto/control.pb.h"
 #include "remoting/proto/video.pb.h"
 #include "remoting/protocol/protocol_mock_objects.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/webrtc/modules/desktop_capture/desktop_frame.h"
 #include "third_party/webrtc/modules/desktop_capture/screen_capturer_mock_objects.h"
 
 using ::remoting::protocol::MockVideoStub;
 
 using ::testing::_;
+using ::testing::AtLeast;
 using ::testing::DoAll;
 using ::testing::Expectation;
 using ::testing::InvokeWithoutArgs;
+using ::testing::Return;
 
 namespace remoting {
 
 namespace {
 
 ACTION(FinishSend) {
   arg1.Run();
 }
 
+scoped_ptr<webrtc::DesktopFrame> CreateNullFrame(
+    webrtc::DesktopCapturer::Callback*) {
+  return nullptr;
+}
+
+scoped_ptr<webrtc::DesktopFrame> CreateUnchangedFrame(
+    webrtc::DesktopCapturer::Callback*) {
+  const webrtc::DesktopSize kSize(800, 640);
+  // updated_region() is already empty by default in new BasicDesktopFrames.
+  return make_scoped_ptr(new webrtc::BasicDesktopFrame(kSize));
+}
+
 }  // namespace
 
 static const int kWidth = 640;
 static const int kHeight = 480;
 
 class ThreadCheckVideoEncoder : public VideoEncoderVerbatim {
  public:
   ThreadCheckVideoEncoder(
       scoped_refptr<base::SingleThreadTaskRunner> task_runner)
       : task_runner_(task_runner) {
@@ skipping 101 matching lines @@
           FinishSend(),
           InvokeWithoutArgs(&run_loop, &base::RunLoop::Quit)))
       .RetiresOnSaturation();
 
   // Start video frame capture.
   pump_.reset(new VideoFramePump(encode_task_runner_,
                                  make_scoped_ptr(new DesktopCapturerProxy(
                                      capture_task_runner_, capturer.Pass())),
                                  encoder.Pass(), &video_stub_));
 
+  // Run MessageLoop until the first frame is received.
+  run_loop.Run();
+}
+
+// Tests that the pump handles null frames returned by the capturer.
+TEST_F(VideoFramePumpTest, NullFrame) {
+  scoped_ptr<FakeDesktopCapturer> capturer(new FakeDesktopCapturer);
+  scoped_ptr<MockVideoEncoder> encoder(new MockVideoEncoder);
+
+  base::RunLoop run_loop;
+
+  // Set up the capturer to return null frames.
+  capturer->set_frame_generator(base::Bind(&CreateNullFrame));
+
+  // Expect that the VideoEncoder::Encode() method is never called.
+  EXPECT_CALL(*encoder, EncodePtr(_)).Times(0);
+
+  // When the first ProcessVideoPacket is received we stop the VideoFramePump.
+  EXPECT_CALL(video_stub_, ProcessVideoPacketPtr(_, _))
+      .WillOnce(DoAll(FinishSend(),
+                      InvokeWithoutArgs(&run_loop, &base::RunLoop::Quit)))
+      .RetiresOnSaturation();
+
+  // Start video frame capture.
+  pump_.reset(new VideoFramePump(encode_task_runner_,
+                                 make_scoped_ptr(new DesktopCapturerProxy(
+                                     capture_task_runner_, capturer.Pass())),
+                                 encoder.Pass(), &video_stub_));
+
   // Run MessageLoop until the first frame is received..
   run_loop.Run();
 }
+
+// Tests how the pump handles unchanged frames returned by the capturer.
+TEST_F(VideoFramePumpTest, UnchangedFrame) {
+  scoped_ptr<FakeDesktopCapturer> capturer(new FakeDesktopCapturer);
+  scoped_ptr<MockVideoEncoder> encoder(new MockVideoEncoder);
+
+  base::RunLoop run_loop;
+
+  // Set up the capturer to return unchanged frames.
+  capturer->set_frame_generator(base::Bind(&CreateUnchangedFrame));
+
+  // Expect that the VideoEncoder::Encode() method is called.
+  EXPECT_CALL(*encoder, EncodePtr(_)).WillRepeatedly(Return(nullptr));
+
+  // When the first ProcessVideoPacket is received we stop the VideoFramePump.
+  // TODO(wez): Verify that the generated packet has no content here.
+  EXPECT_CALL(video_stub_, ProcessVideoPacketPtr(_, _))
+      .WillOnce(DoAll(FinishSend(),
+                      InvokeWithoutArgs(&run_loop, &base::RunLoop::Quit)))
+      .RetiresOnSaturation();
+
+  // Start video frame capture.
+  pump_.reset(new VideoFramePump(encode_task_runner_,
+                                 make_scoped_ptr(new DesktopCapturerProxy(
+                                     capture_task_runner_, capturer.Pass())),
+                                 encoder.Pass(), &video_stub_));
+
+  // Run MessageLoop until the first frame is received..
+  run_loop.Run();
+}
 
 }  // namespace remoting