Cleanup of webrtc::VideoFrame.

Delete EqualsFrame method, used only by tests. Delete one of the
CreateFrame methods. Drop return value for CreateEmptyFrame, CreateFrame
and CopyFrame.

BUG=webrtc:5426

Review URL: https://codereview.webrtc.org/1679323002

Cr-Commit-Position: refs/heads/master@{#11783}
diff --git a/webrtc/modules/modules.gyp b/webrtc/modules/modules.gyp
index 68e4d11..465c5ba 100644
--- a/webrtc/modules/modules.gyp
+++ b/webrtc/modules/modules.gyp
@@ -160,7 +160,7 @@
             '<(webrtc_root)/modules/video_coding/codecs/vp8/vp8.gyp:webrtc_vp8',
             '<(webrtc_root)/modules/video_coding/codecs/vp9/vp9.gyp:webrtc_vp9',
             '<(webrtc_root)/system_wrappers/system_wrappers.gyp:system_wrappers',
-            '<(webrtc_root)/test/test.gyp:fake_video_frames',
+            '<(webrtc_root)/test/test.gyp:video_test_common',
             '<(webrtc_root)/test/test.gyp:rtp_test_utils',
             '<(webrtc_root)/test/test.gyp:test_support_main',
             '<(webrtc_root)/test/webrtc_test_common.gyp:webrtc_test_common',