Add a JS API for detecting WebGL availability.

content/browser/gpu/gpu_data_manager.h

Index: content/browser/gpu/gpu_data_manager.h
===================================================================
--- content/browser/gpu/gpu_data_manager.h	(revision 112547)
+++ content/browser/gpu/gpu_data_manager.h	(working copy)
@@ -47,6 +47,10 @@
 
   const content::GPUInfo& gpu_info() const;
 
+  bool complete_gpu_info_available() const {
+    return complete_gpu_info_available_;
+  }
+
   // Returns status of various GPU features. This is two parted:
   // {
   //    featureStatus: []
@@ -222,6 +226,7 @@
   void EnableSoftwareRenderingIfNecessary();
 
   bool complete_gpu_info_already_requested_;
+  bool complete_gpu_info_available_;

[Ken Russell (switch to Gerrit), 2011/12/03 02:59:42]

I don't fully understand the threading model in this code, but is this variable
written and tested by different threads?

 
   GpuFeatureFlags gpu_feature_flags_;
   GpuFeatureFlags preliminary_gpu_feature_flags_;