Add a JS API for detecting WebGL availability.

chrome/browser/extensions/extension_webstore_private_api.cc

Index: chrome/browser/extensions/extension_webstore_private_api.cc
===================================================================
--- chrome/browser/extensions/extension_webstore_private_api.cc	(revision 112998)
+++ chrome/browser/extensions/extension_webstore_private_api.cc	(working copy)
@@ -491,3 +491,58 @@
   prefs->SetWebStoreLogin(login);
   return true;
 }
+
+GetWebGLStatusFunction::GetWebGLStatusFunction() {}
+GetWebGLStatusFunction::~GetWebGLStatusFunction() {}
+
+// static
+bool GetWebGLStatusFunction::IsWebGLAllowed(GpuDataManager* manager) {
+  bool webgl_allowed = true;
+  if (!manager->GpuAccessAllowed()) {
+    webgl_allowed = false;
+  } else {
+    uint32 blacklist_flags = manager->GetGpuFeatureFlags().flags();
+    if (blacklist_flags & GpuFeatureFlags::kGpuFeatureWebgl)
+      webgl_allowed = false;
+  }
+  return webgl_allowed;
+}
+
+void GetWebGLStatusFunction::OnGpuInfoUpdate() {
+  GpuDataManager* manager = GpuDataManager::GetInstance();
+  manager->RemoveObserver(this);
+  bool webgl_allowed = IsWebGLAllowed(manager);
+  result_.reset(Value::CreateStringValue(

[Mihai Parparita -not on Chrome, 2011/12/06 02:58:11]

Rather than repeating the result creation code twice, can you move it to a
helper CreateResult method?

[Zhenyao Mo, 2011/12/06 20:00:15]

Done.

+      webgl_allowed ? "webgl_allowed" : "webgl_blocked"));
+  SendResponse(true);
+
+  Release();

[Mihai Parparita -not on Chrome, 2011/12/06 02:58:11]

The convention in extensions code is to add comments next to Release/AddRef
calls indicating where they get balanced (see uses elsewhere in this file).

[Zhenyao Mo, 2011/12/06 20:00:15]

Done.

+}
+
+bool GetWebGLStatusFunction::RunImpl() {
+  bool finalized = true;
+#if defined(OS_LINUX)
+  finalized = false;
+#endif
+
+  GpuDataManager* manager = GpuDataManager::GetInstance();
+  if (manager->complete_gpu_info_available())
+    finalized = true;
+
+  bool webgl_allowed = IsWebGLAllowed(manager);
+  if (!webgl_allowed)
+    finalized = true;

[Mihai Parparita -not on Chrome, 2011/12/06 02:58:11]

This confused me initially, perhaps add comments to IsWebGLAllowed indicating
that a false return value is always valid, but a true one is only valid if GPU
info has been loaded?

[Zhenyao Mo, 2011/12/06 20:00:15]

Done.  Added comment in .h file

+
+  if (finalized) {
+    result_.reset(Value::CreateStringValue(
+        webgl_allowed ? "webgl_allowed" : "webgl_blocked"));
+    SendResponse(true);
+  } else {
+    AddRef();
+
+    manager->AddObserver(this);
+    manager->RequestCompleteGpuInfoIfNeeded();
+  }
+  return true;
+}
+