WebGL feature will only enabled when accelerated

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 5bd58166d21c06128803323d55d75381bfd7dfc4..f9ec8e15bbc599cf857e0bf7ba428bb50aa28efb 100644
--- a/content/browser/gpu/gpu_data_manager_impl_private.cc
+++ b/content/browser/gpu/gpu_data_manager_impl_private.cc
@@ -933,8 +933,13 @@ void GpuDataManagerImplPrivate::DisableHardwareAcceleration() {
 
   card_blacklisted_ = true;
 
-  for (int i = 0; i < gpu::NUMBER_OF_GPU_FEATURE_TYPES; ++i)
-    blacklisted_features_.insert(i);
+  for (int i = 0; i < gpu::NUMBER_OF_GPU_FEATURE_TYPES; ++i) {
+    if ((i != gpu::GPU_FEATURE_TYPE_SWIFTSHADER) ||
+        base::CommandLine::ForCurrentProcess()->HasSwitch(
+            switches::kDisableSoftwareRasterizer)) {

[Zhenyao Mo, 2017/03/09 19:18:03]

Consider this situation: on a system where kDisableSoftwareRasterizer is passed,
and accelerated WebGL is blacklisted.

You will still want the SwiftShader for WebGL, but not for Rasterizer.

What you did here is not to allow SwiftShader for WebGL, which I think it's an
overkill.

[sugoi1, 2017/03/09 19:24:33]

Ok, but this isn't new, I simply moved it from
GpuDataManagerImplPrivate::EnableSwiftShaderIfNecessary() below. I can remove it
if it's wrong.

[sugoi1, 2017/03/09 20:07:12]

Removed kDisableSoftwareRasterizer check.

[sugoi1, 2017/03/09 20:17:07]

Wait a second, I just looked into it and the kDisableSoftwareRasterizer flag is
only used to disable SwiftShader and the description mentions a 3D software
rasterizer, so I think this was correct before.

+      blacklisted_features_.insert(i);
+    }
+  }
 
   EnableSwiftShaderIfNecessary();
   NotifyGpuInfoUpdate();
@@ -1231,6 +1236,11 @@ void GpuDataManagerImplPrivate::UpdateBlacklistedFeatures(
     blacklisted_features_.insert(gpu::GPU_FEATURE_TYPE_WEBGL);
   }
 
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kDisableSoftwareRasterizer)) {
+    blacklisted_features_.insert(gpu::GPU_FEATURE_TYPE_SWIFTSHADER);

[Zhenyao Mo, 2017/03/09 19:18:03]

Same here.

[sugoi1, 2017/03/09 20:07:12]

Removed this change.

+  }
+
   EnableSwiftShaderIfNecessary();
 }
 
@@ -1257,11 +1267,10 @@ void GpuDataManagerImplPrivate::NotifyGpuInfoUpdate() {
 }
 
 void GpuDataManagerImplPrivate::EnableSwiftShaderIfNecessary() {
-  if (!GpuAccessAllowed(NULL) ||
+  if (!GpuAccessAllowed(nullptr) ||
       blacklisted_features_.count(gpu::GPU_FEATURE_TYPE_WEBGL)) {
     if (!swiftshader_path_.empty() &&
-        !base::CommandLine::ForCurrentProcess()->HasSwitch(
-             switches::kDisableSoftwareRasterizer))
+        !blacklisted_features_.count(gpu::GPU_FEATURE_TYPE_SWIFTSHADER))
       use_swiftshader_ = true;
   }
 }