[chromecast] enable accelerated video decode

Enable accelerated video decode for Cast devices that
supports v4l2 codec.

Bug: internal b/174596074
Test: manual on device
Change-Id: I650a997309b2edb51721baec94cfd034b13f655f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2568857Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Yuchen Liu <yucliu@chromium.org>
Reviewed-by: Dan Sanders <sandersd@chromium.org>
Commit-Queue: Peter Qiu <zqiu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#835005}

chromecast/browser/BUILD.gn

@@ -247,6 +247,7 @@ cast_source_set("browser_base") {
     "//gpu",
     "//ipc",
     "//media",
+    "//media/gpu:buildflags",
     "//media/mojo/mojom:remoting",
     "//media/mojo/services",
     "//mojo/public/cpp/bindings",

chromecast/browser/DEPS

@@ -52,6 +52,7 @@ include_rules = [
   "+gpu/command_buffer/service/gpu_switches.h",
   "+media/audio",
   "+media/base",
+  "+media/gpu",
   "+media/mojo",
   "+mojo/public",
   "+net",

chromecast/browser/cast_content_browser_client.cc

@@ -80,6 +80,7 @@
 #include "content/public/common/url_constants.h"
 #include "media/audio/audio_thread_impl.h"
 #include "media/base/media_switches.h"
+#include "media/gpu/buildflags.h"
 #include "media/mojo/services/mojo_renderer_service.h"
 #include "mojo/public/cpp/bindings/pending_receiver.h"
 #include "net/ssl/ssl_cert_request_info.h"
@@ -167,6 +168,10 @@ CastContentBrowserClient::CastContentBrowserClient(
 #if defined(OS_ANDROID) && BUILDFLAG(ENABLE_VIDEO_CAPTURE_SERVICE)
         features::kMojoVideoCapture,
 #endif
+#if BUILDFLAG(USE_V4L2_CODEC)
+        // Enable accelerated video decode if v4l2 codec is supported.
+        ::media::kVaapiVideoDecodeLinux,
+#endif  // BUILDFLAG(USE_V4L2_CODEC)
   });
 
   cast_feature_list_creator_->SetExtraDisableFeatures({