Teach GPU command buffer whether a context is webgl.

gpu/command_buffer/service/feature_info.cc

Index: gpu/command_buffer/service/feature_info.cc
diff --git a/gpu/command_buffer/service/feature_info.cc b/gpu/command_buffer/service/feature_info.cc
index c86de231fd4695af0574699fbab0570a12d47675..d692b546ed4885cc1f536207cd212eb0a3a4b518 100644
--- a/gpu/command_buffer/service/feature_info.cc
+++ b/gpu/command_buffer/service/feature_info.cc
@@ -523,10 +523,11 @@ void FeatureInfo::InitializeFeatures() {
   }
 
   // Check if we should allow GL_OES_texture_npot
-  if (gl_version_info_->is_es3 ||
-      gl_version_info_->is_desktop_core_profile ||
-      extensions.Contains("GL_ARB_texture_non_power_of_two") ||
-      extensions.Contains("GL_OES_texture_npot")) {
+  if (!disallowed_features_.npot_support &&

[Zhenyao Mo, 2015/06/07 21:42:11]

This is where we disable NPOT support for WebGL 1.  Note that handling of
falling back to (0, 0, 0, 1) is emulated in command buffer, not delegating to
underlying driver even when NPOT support isn't reported by the driver.

+      (gl_version_info_->is_es3 ||
+       gl_version_info_->is_desktop_core_profile ||
+       extensions.Contains("GL_ARB_texture_non_power_of_two") ||
+       extensions.Contains("GL_OES_texture_npot"))) {
     AddExtensionString("GL_OES_texture_npot");
     feature_flags_.npot_ok = true;
   }