Add rtc_media as a direct dependency of rtc_media_unittests.

Without this, the rtc_media_unittests target was only an indirect
dependency, and compiled without HAVE_WEBRTC_VIDEO. And some testcases,
in particular, all tests defined by webrtcvideocapturer_unittest.cc,
are excluded from rtc_media_unittests.

BUG=

Review-Url: https://codereview.webrtc.org/2250433008
Cr-Commit-Position: refs/heads/master@{#13859}

webrtc/media/engine/webrtcvideoframefactory.h

@@ -20,6 +20,11 @@ struct CapturedFrame;
 // Creates instances of cricket::WebRtcVideoFrame.
 class WebRtcVideoFrameFactory : public VideoFrameFactory {
  public:
+  // Note: Overriding a method name overrides all overloaded versions.
+  // Without this using-declaration, we would hide the 5-argument
+  // method we want to inherit.
+  using VideoFrameFactory::CreateAliasedFrame;
+
   VideoFrame* CreateAliasedFrame(const CapturedFrame* aliased_frame,
                                  int width,
                                  int height) const override;

webrtc/media/media.gyp

@@ -254,6 +254,7 @@
             '<(webrtc_root)/base/base_tests.gyp:rtc_base_tests_utils',
             '<(webrtc_root)/system_wrappers/system_wrappers.gyp:metrics_default',
             '<(webrtc_root)/test/test.gyp:test_support',
+            'rtc_media',
             'rtc_unittest_main',
           ],
           'sources': [