Add virtual layout test for GPU accelerated decoding.

third_party/WebKit/LayoutTests/VirtualTestSuites

 [
   {
     "prefix": "gpu",
     "base": "fast/canvas",
     "args": ["--enable-accelerated-2d-canvas",
              "--disable-display-list-2d-canvas"]
   },
   {
     "prefix": "display_list_2d_canvas",
     "base": "fast/canvas",
@@ skipping 75 matching lines @@
     "prefix": "android",
     "base": "fullscreen",
     "args": ["--enable-threaded-compositing",
              "--enable-fixed-position-compositing", "--enable-prefer-compositing-to-lcd-text",
              "--enable-composited-scrolling-for-frames", "--enable-gesture-tap-highlight", "--enable-pinch",
              "--force-overlay-fullscreen-video", "--enable-overlay-scrollbars", "--enable-overscroll-notifications",
              "--enable-fixed-layout", "--enable-viewport", "--disable-canvas-aa",
              "--disable-composited-antialiasing"]
   },
   {
+    "prefix": "media-gpu-accelerated",
+    "base": "http/tests/media/media-source",
+    "args": ["--enable-unified-media-pipeline", "--use-gpu-in-tests"]
+  },
+  {
     "prefix": "android",
     "base": "media/mediadocument",
     "args": ["--enable-features=MediaDocumentDownloadButton"]
   },
   {
     "prefix": "stable",
     "base": "fast/css3-text/css3-text-decoration/stable",
     "args": ["--stable-release-mode"]
   },
   {
@@ skipping 136 matching lines @@
     "prefix": "documentwriteevaluator",
     "base": "http/tests/preload/document-write",
     "args": ["--enable-blink-features=DocumentWriteEvaluator"]
   },
   {
     "prefix": "asyncawait",
     "base": "inspector/sources/debugger-async/async-await",
     "args": ["--js-flags=--harmony-async-await"]
   }
 ]