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

content/browser/gpu/gpu_data_manager_impl_private.h

Index: content/browser/gpu/gpu_data_manager_impl_private.h
diff --git a/content/browser/gpu/gpu_data_manager_impl_private.h b/content/browser/gpu/gpu_data_manager_impl_private.h
index 8e5514fad318236925412283a590aeb13884e9ef..61c1988bea4e06b4570f242ab033edd94f07d03d 100644
--- a/content/browser/gpu/gpu_data_manager_impl_private.h
+++ b/content/browser/gpu/gpu_data_manager_impl_private.h
@@ -42,6 +42,7 @@ class CONTENT_EXPORT GpuDataManagerImplPrivate {
   void RequestVideoMemoryUsageStatsUpdate() const;
   bool ShouldUseSwiftShader() const;
   void RegisterSwiftShaderPath(const base::FilePath& path);
+  bool ShouldUseWarp() const;
   void AddObserver(GpuDataManagerObserver* observer);
   void RemoveObserver(GpuDataManagerObserver* observer);
   void UnblockDomainFrom3DAPIs(const GURL& url);
@@ -127,6 +128,8 @@ class CONTENT_EXPORT GpuDataManagerImplPrivate {
   FRIEND_TEST_ALL_PREFIXES(GpuDataManagerImplPrivateTest,
                            SwiftShaderRendering2);
   FRIEND_TEST_ALL_PREFIXES(GpuDataManagerImplPrivateTest,
+                           WarpEnabledOverridesSwiftShader);
+  FRIEND_TEST_ALL_PREFIXES(GpuDataManagerImplPrivateTest,
                            GpuInfoUpdate);
   FRIEND_TEST_ALL_PREFIXES(GpuDataManagerImplPrivateTest,
                            NoGpuInfoUpdateWithSwiftShader);
@@ -201,6 +204,13 @@ class CONTENT_EXPORT GpuDataManagerImplPrivate {
   // Try to switch to SwiftShader rendering, if possible and necessary.
   void EnableSwiftShaderIfNecessary();
 
+  // Try to switch to WARP rendering if the GPU hardware is not supported or
+  // absent, and if we are trying to run in Windows Metro mode.
+  void EnableWarpIfNecessary();
+
+  // Use only for testing, forces |use_warp_| to true.
+  void ForceWarpModeForTesting();
+
   // Helper to extract the domain from a given URL.
   std::string GetDomainFromURL(const GURL& url) const;
 
@@ -231,6 +241,8 @@ class CONTENT_EXPORT GpuDataManagerImplPrivate {
 
   bool use_swiftshader_;
 
+  bool use_warp_;
+
   base::FilePath swiftshader_path_;
 
   // Current card force-blacklisted due to GPU crashes, or disabled through