Add virtual layout test for GPU accelerated decoding.

third_party/WebKit/LayoutTests/virtual/media-gpu-accelerated/http/tests/media/media-source/README.txt

Index: third_party/WebKit/LayoutTests/virtual/media-gpu-accelerated/http/tests/media/media-source/README.txt
diff --git a/third_party/WebKit/LayoutTests/virtual/media-gpu-accelerated/http/tests/media/media-source/README.txt b/third_party/WebKit/LayoutTests/virtual/media-gpu-accelerated/http/tests/media/media-source/README.txt
new file mode 100644
index 0000000000000000000000000000000000000000..01d9d8009c702dedb745ff94cea26e3f595654ac
--- /dev/null
+++ b/third_party/WebKit/LayoutTests/virtual/media-gpu-accelerated/http/tests/media/media-source/README.txt
@@ -0,0 +1,38 @@
+OVERVIEW OF MEDIA-GPU-ACCELERATED TESTS
+
+The media-gpu-accelerated prefix is common to a handful of virtual tests that

[chcunningham, 2016/07/16 00:57:51]

Note to self - fix this comment if we stick with one test (likely)

[chcunningham, 2016/07/16 19:02:59]

Done.

+need extra flags perform hardware accelerated video decoding on android bots.
+
+TODO(chcunningham): Explore enabling hardware acceleration for desktop bots.
+Non-android bots do not currently test with proprietary codecs, which translates
+to no hardware acceleration.
+
+Android only runs a small subset of layout tests (see SmokeTests file), so
+for now we specify the full paths of the tests we use in SmokeTests to minimize
+the penalty for desktop bots.
+
+These tests all add the same flag:
+    --use-gpu-in-tests
+
+Layout tests generally run using Mesa (see http://crrev.com/23868030) to
+to produce more stable output for pixel layout tests when running on different
+devices. However, Mesa is not compatible with android's SurfaceTexture,
+used in in HW accelerated video decoding (H264 in mp4). We specify
+use-gpu-in-tests to override the MesaGL default.
+
+
+WHY ADD THESE TESTS TO SMOKETESTS

[chcunningham, 2016/07/16 00:57:51]

Note to self - CL description is probably a better place for this.

[chcunningham, 2016/07/16 19:02:59]

Done.

+
+mediasource-config-change-mp4-av-video-framesize.html:
+This test simulates an interesting adaptive playback scenario by reconfiguring
+the size of the video midstream. Config changes test the flushing and
+reconfiguration of Android's MediaCodec (historically problematic).
+
+mediasource-config-change-mp4-av-audio-bitrate.html:
+Android's audio driver is distinct from desktop platforms so this test was
+chosen as interesting test for the audio path to cover basic/variable-bitrate
+audio playback.
+
+mediasource-config-change-mp4-v-framerate.html:
+This test simulates an interesting adaptive playback by varying the framerate of
+the video midstream. Its also nice coverage of video-without-audio playback.