adds WARP support to Chromium, for Metro mode only, on Windows 8

content/browser/gpu/gpu_data_manager_impl_private.cc

Index: content/browser/gpu/gpu_data_manager_impl_private.cc
diff --git a/content/browser/gpu/gpu_data_manager_impl_private.cc b/content/browser/gpu/gpu_data_manager_impl_private.cc
index bbf7231c954858ff4828b1745ea994a9b177050f..3ca5d6d34b92588c3696cc4b690a37bc994b4afb 100644
--- a/content/browser/gpu/gpu_data_manager_impl_private.cc
+++ b/content/browser/gpu/gpu_data_manager_impl_private.cc
@@ -271,7 +271,7 @@ bool GpuDataManagerImplPrivate::IsFeatureBlacklisted(int feature) const {
     return true;
   }
 #endif  // OS_CHROMEOS
-  if (use_swiftshader_) {
+  if (use_swiftshader_ || gpu_info_.use_warp) {
     // Skia's software rendering is probably more efficient than going through
     // software emulation of the GPU, so use that.
     if (feature == gpu::GPU_FEATURE_TYPE_ACCELERATED_2D_CANVAS)
@@ -287,7 +287,7 @@ bool GpuDataManagerImplPrivate::IsDriverBugWorkaroundActive(int feature) const {
 }
 
 size_t GpuDataManagerImplPrivate::GetBlacklistedFeatureCount() const {
-  if (use_swiftshader_)
+  if (use_swiftshader_ || gpu_info_.use_warp)
     return 1;
   return blacklisted_features_.size();
 }
@@ -311,7 +311,7 @@ void GpuDataManagerImplPrivate::GetGpuProcessHandles(
 
 bool GpuDataManagerImplPrivate::GpuAccessAllowed(
     std::string* reason) const {
-  if (use_swiftshader_)
+  if (use_swiftshader_ || gpu_info_.use_warp)
     return true;
 
   if (!gpu_process_accessible_) {
@@ -471,6 +471,18 @@ void GpuDataManagerImplPrivate::GetGLStrings(std::string* gl_vendor,
   *gl_version = gpu_info_.gl_version;
 }
 
+void GpuDataManagerImplPrivate::SetShouldUseWarp(bool use_warp) {
+  gpu_info_.use_warp = use_warp;

[Zhenyao Mo, 2014/08/20 21:02:09]

This is incorrect.  gpu_info_ could be updated multiple times during chrome
lifetime and this state will be lost.

You need a separate use_warp_ variable outside gpu_info_.

[luken, 2014/08/27 20:43:46]

Deprecated code.

+  // Let the observers know, particularly the GpuPrefManager, so it can update
+  // its persistent state about using warp or not.
+  NotifyGpuInfoUpdate();
+}
+
+bool GpuDataManagerImplPrivate::ShouldUseWarp() const {
+  return gpu_info_.use_warp ||
+      base::CommandLine::ForCurrentProcess()->HasSwitch(switches::kUseWarp);
+}
+
 void GpuDataManagerImplPrivate::Initialize() {
   TRACE_EVENT0("startup", "GpuDataManagerImpl::Initialize");
   if (finalized_) {
@@ -545,7 +557,7 @@ void GpuDataManagerImplPrivate::UpdateGpuInfoHelper() {
 
 void GpuDataManagerImplPrivate::UpdateGpuInfo(const gpu::GPUInfo& gpu_info) {
   // No further update of gpu_info if falling back to SwiftShader.
-  if (use_swiftshader_)
+  if (use_swiftshader_ || gpu_info_.use_warp)
     return;
 
   gpu::MergeGPUInfo(&gpu_info_, gpu_info);
@@ -645,6 +657,9 @@ void GpuDataManagerImplPrivate::AppendGpuCommandLine(
       gpu_info_.driver_vendor);
   command_line->AppendSwitchASCII(switches::kGpuDriverVersion,
       gpu_info_.driver_version);
+
+  if (ShouldUseWarp())
+    command_line->AppendSwitch(switches::kUseWarp);
 }
 
 void GpuDataManagerImplPrivate::AppendPluginCommandLine(
@@ -819,6 +834,8 @@ bool GpuDataManagerImplPrivate::UpdateActiveGpu(
 }
 
 bool GpuDataManagerImplPrivate::CanUseGpuBrowserCompositor() const {
+  if (gpu_info_.use_warp)

[Zhenyao Mo, 2014/08/20 21:02:09]

You should use ShouldUseWarp() here to be consistent.

[luken, 2014/08/27 20:43:46]

Done.

+    return true;
   if (ShouldUseSwiftShader())
     return false;
   if (IsFeatureBlacklisted(gpu::GPU_FEATURE_TYPE_GPU_COMPOSITING))