Enable image capture tests with real webcams using video capture service

This is an attempt to enable tests that had been disabled due to flakiness on
webrtc bots. There is hope that the flakiness is resolved by the tests now
being run sequentially since [1] and [2] have landed.

The test pass when I run them on my local machine.

[1] https://chromium-review.googlesource.com/872260
[2] https://chromium-review.googlesource.com/876003

Test: content_browsertests --gtest_filter=UsingRealWebcam* --run-manual --test-launcher-jobs=1

Bug: 733582
Change-Id: If536e4c0b87c0a7de50ffc35f8c0a1d9abc52359
Reviewed-on: https://chromium-review.googlesource.com/894883Reviewed-by: Emircan Uysaler <emircan@chromium.org>
Commit-Queue: Christian Fremerey <chfremer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#533325}

content/browser/webrtc/webrtc_image_capture_browsertest.cc

@@ -168,18 +168,6 @@ class WebRtcImageCaptureSucceedsBrowserTest
 #endif
   }
 
-  bool RunImageCaptureTestCase(const std::string& command) override {
-    // TODO(chfremer): Enable test cases using the video capture service with
-    // real cameras as soon as root cause for https://crbug.com/733582 is
-    // understood and resolved.
-    if ((std::get<0>(GetParam()) == TargetCamera::REAL_WEBCAM) &&
-        (std::get<1>(GetParam()).use_video_capture_service)) {
-      LOG(INFO) << "Skipping this test case";
-      return true;
-    }
-    return WebRtcImageCaptureBrowserTestBase::RunImageCaptureTestCase(command);
-  }
-
  private:
   base::test::ScopedFeatureList scoped_feature_list_;