chromecast: force disable new accelerated video decoder

The new accelerated video decoder uses V4L2SliceVDA, which is
not supported by Cast devices.

So instead, we will force disable use of this new decoder
through command line switch, which will fallback to use
VdaVideoDecoder, which uses V4L2VDA.

Bug: b/158230739
Test: Verify mirroring on Cast display devices
Change-Id: I7765e6861c09a0357e2d923a20c9a56c1bdcb065
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2238876Reviewed-by: Thomas Guilbert <tguilbert@chromium.org>
Reviewed-by: Sean Topping <seantopping@chromium.org>
Reviewed-by: Luke Halliwell (slow) <halliwell@chromium.org>
Reviewed-by: Yuchen Liu <yucliu@chromium.org>
Commit-Queue: Peter Qiu <zqiu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#776861}

chromecast/browser/DEPS

@@ -48,6 +48,7 @@ include_rules = [
   "+extensions/shell/browser/api",
   "+gin/v8_initializer.h",
   "+gpu/command_buffer/service/gpu_switches.h",
+  "+media",
   "+media/audio",
   "+media/base",
   "+media/mojo",

chromecast/browser/cast_browser_main_parts.cc

@@ -69,6 +69,7 @@
 #include "gpu/command_buffer/service/gpu_switches.h"
 #include "media/base/media.h"
 #include "media/base/media_switches.h"
+#include "media/media_buildflags.h"
 #include "net/base/network_change_notifier.h"
 #include "services/network/public/cpp/shared_url_loader_factory.h"
 #include "ui/base/ui_base_switches.h"
@@ -327,6 +328,11 @@ const DefaultCommandLineSwitch kDefaultSwitches[] = {
 #endif
 #endif
 #endif  // defined(OS_LINUX)
+#if BUILDFLAG(USE_CHROMEOS_MEDIA_ACCELERATION)
+    // Force disable new video decoder, since it uses slice H.264, which is
+    // not currently supported on Linux-based Cast devices.
+    {switches::kForceDisableNewAcceleratedVideoDecoder, ""},
+#endif  // BUILDFLAG(USE_CHROMEOS_MEDIA_ACCELERATION)
     // It's better to start GPU process on demand. For example, for TV platforms
     // cast starts in background and can't render until TV switches to cast
     // input.