Don't disable viz on video chromecast builds with --disable-gpu

This should work like other platforms, and give a Viz process that
doesn't require a hardware GPU, e.g. for running tests on infra.

This fixes an infinite loop when --disable-gpu is passed in such builds,
where we try to start a GPU process but this is rejected by
GpuProcessStartAllowed() == false. This started happening (or at least
became severe enough to break our tests) after 966e62f6
("[scheduler] Enable prioritize until begin main frame by default.").

Change-Id: I67c4f819e0383950d1c876bc34b799fb794bd5e7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2304154Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Commit-Queue: Michael Spang <spang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#789655}

content/browser/BUILD.gn

@@ -2082,6 +2082,10 @@ jumbo_source_set("browser") {
     ]
   }
 
+  if (is_chromecast) {
+    deps += [ "//chromecast:chromecast_buildflags" ]
+  }
+
   if (is_chromecast && is_linux) {
     sources += [
       "tracing/cast_tracing_agent.cc",

content/browser/gpu/DEPS

 include_rules = [
+  "+chromecast/chromecast_buildflags.h",
   "+components/metal_util",
   "+components/ui_devtools/buildflags.h",
 ]

content/browser/gpu/gpu_data_manager_impl_private.cc

@@ -91,6 +91,9 @@
 #include "base/win/windows_version.h"
 #include "ui/display/win/screen_win.h"
 #endif  // OS_WIN
+#if BUILDFLAG(IS_CHROMECAST)
+#include "chromecast/chromecast_buildflags.h"
+#endif
 
 namespace content {
 
@@ -563,8 +566,10 @@ void GpuDataManagerImplPrivate::InitializeGpuModes() {
     // Chomecast audio-only builds run with the flag --disable-gpu. The GPU
     // process should not be started in this case.
 #if BUILDFLAG(IS_CHROMECAST)
+#if BUILDFLAG(IS_CAST_AUDIO_ONLY)
     fallback_modes_.clear();
     fallback_modes_.push_back(gpu::GpuMode::DISABLED);
+#endif
 #elif defined(OS_ANDROID) || defined(OS_CHROMEOS)
     CHECK(false) << "GPU acceleration is required on certain platforms!";
 #endif  // IS_CHROMECAST

content/browser/gpu/gpu_data_manager_impl_private_unittest.cc

@@ -26,6 +26,13 @@
 #include "testing/gtest/include/gtest/gtest.h"
 #include "url/gurl.h"
 
+#if BUILDFLAG(IS_CHROMECAST)
+#include "chromecast/chromecast_buildflags.h"
+#if BUILDFLAG(IS_CAST_AUDIO_ONLY)
+#define CAST_AUDIO_ONLY
+#endif
+#endif
+
 namespace content {
 namespace {
 
@@ -292,7 +299,7 @@ TEST_F(GpuDataManagerImplPrivateTest, FallbackWithSwiftShaderDisabled) {
 }
 #endif  // !OS_FUCHSIA
 
-#if !BUILDFLAG(IS_CHROMECAST)
+#if !defined(CAST_AUDIO_ONLY)
 TEST_F(GpuDataManagerImplPrivateTest, GpuStartsWithGpuDisabled) {
   base::CommandLine::ForCurrentProcess()->AppendSwitch(switches::kDisableGpu);
   ScopedGpuDataManagerImplPrivate manager;
@@ -302,7 +309,7 @@ TEST_F(GpuDataManagerImplPrivateTest, GpuStartsWithGpuDisabled) {
 #endif  // !OS_ANDROID && !OS_CHROMEOS
 
 // Chromecast audio-only builds should not launch the GPU process.
-#if BUILDFLAG(IS_CHROMECAST)
+#if defined(CAST_AUDIO_ONLY)
 TEST_F(GpuDataManagerImplPrivateTest, ChromecastStartsWithGpuDisabled) {
   base::CommandLine::ForCurrentProcess()->AppendSwitch(switches::kDisableGpu);
   ScopedGpuDataManagerImplPrivate manager;

content/test/BUILD.gn

@@ -2417,6 +2417,10 @@ test("content_unittests") {
     sources += [ "../browser/xr/service/xr_runtime_manager_unittest.cc" ]
     deps += [ "//device/vr:vr_fakes" ]
   }
+
+  if (is_chromecast) {
+    deps += [ "//chromecast:chromecast_buildflags" ]
+  }
 }
 
 if (enable_nocompile_tests) {