video_loopback: fall back to fake capturer if we can't open camera.

webrtc/video/video_quality_test.cc

 /*
  *  Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 #include "webrtc/video/video_quality_test.h"
@@ skipping 1224 matching lines @@
   if (params_.screenshare.enabled) {
     test::FrameGeneratorCapturer* frame_generator_capturer =
         new test::FrameGeneratorCapturer(clock_, frame_generator_.release(),
                                          params_.video.fps);
     EXPECT_TRUE(frame_generator_capturer->Init());
     video_capturer_.reset(frame_generator_capturer);
   } else {
     if (params_.video.clip_name.empty()) {
       video_capturer_.reset(test::VcmCapturer::Create(
           params_.video.width, params_.video.height, params_.video.fps));
+      if (!video_capturer_) {
+        // Failed to get actual camera, use chroma generator as backup.
+        video_capturer_.reset(test::FrameGeneratorCapturer::Create(
+            params_.video.width, params_.video.height, params_.video.fps,
+            clock_));
+      }
     } else {
       video_capturer_.reset(test::FrameGeneratorCapturer::CreateFromYuvFile(
           test::ResourcePath(params_.video.clip_name, "yuv"),
           params_.video.width, params_.video.height, params_.video.fps,
           clock_));
       ASSERT_TRUE(video_capturer_) << "Could not create capturer for "
                                    << params_.video.clip_name
                                    << ".yuv. Is this resource file present?";
     }
   }
+  RTC_DCHECK(video_capturer_.get());
 }
 
 void VideoQualityTest::RunWithAnalyzer(const Params& params) {
   params_ = params;
 
   RTC_CHECK(!params_.audio.enabled);
   // TODO(ivica): Merge with RunWithRenderer and use a flag / argument to
   // differentiate between the analyzer and the renderer case.
   CheckParams();
 
@@ skipping 297 matching lines @@
     std::ostringstream str;
     str << receive_logs_++;
     std::string path =
         params_.video.encoded_frame_base_path + "." + str.str() + ".recv.ivf";
     stream->EnableEncodedFrameRecording(rtc::CreatePlatformFile(path),
                                         10000000);
   }
 }
 
 }  // namespace webrtc