Update VideoFramePump to pass un-changed frames to encoders.

remoting/host/video_frame_pump_unittest.cc

Index: remoting/host/video_frame_pump_unittest.cc
diff --git a/remoting/host/video_frame_pump_unittest.cc b/remoting/host/video_frame_pump_unittest.cc
index cd5cd016f6abd6c2587d92bd1213ef03f51a65e8..f72644bffd4a8d1f66b99b7a61c8d2a9ee4a4806 100644
--- a/remoting/host/video_frame_pump_unittest.cc
+++ b/remoting/host/video_frame_pump_unittest.cc
@@ -26,9 +26,11 @@
 using ::remoting::protocol::MockVideoStub;
 
 using ::testing::_;
+using ::testing::AtLeast;
 using ::testing::DoAll;
 using ::testing::Expectation;
 using ::testing::InvokeWithoutArgs;
+using ::testing::Return;
 
 namespace remoting {
 
@@ -38,6 +40,18 @@ 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;
@@ -159,6 +173,65 @@ TEST_F(VideoFramePumpTest, StartAndStop) {
                                      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();
 }