extensions: Register 'app' and 'webstore' bindings only if they are available.

extensions/renderer/dispatcher.cc

Index: extensions/renderer/dispatcher.cc
diff --git a/extensions/renderer/dispatcher.cc b/extensions/renderer/dispatcher.cc
index f27eba89d7aa253ff021d15e56cd78abeec0cd75..c30f91d16c04d5de9b993549178c5364bef07c04 100644
--- a/extensions/renderer/dispatcher.cc
+++ b/extensions/renderer/dispatcher.cc
@@ -1003,8 +1003,11 @@ void Dispatcher::UpdateBindingsForContext(ScriptContext* context) {
     case Feature::BLESSED_WEB_PAGE_CONTEXT: {
       // Web page context; it's too expensive to run the full bindings code.
       // Hard-code that the app and webstore APIs are available...
-      RegisterBinding("app", context);
-      RegisterBinding("webstore", context);
+      if (IsApiAvailable(std::string("app"), context))

[not at google - send to devlin, 2014/08/05 22:43:39]

it's easier to do

if (context->GetAvailability("app").is_available())
  ...

and below.

[sadrul, 2014/08/05 22:51:02]

Nice! Done.

+        RegisterBinding("app", context);
+
+      if (IsApiAvailable(std::string("webstore"), context))

[not at google - send to devlin, 2014/08/05 22:43:39]

also, no need to explicitly construct a std::string here.

[sadrul, 2014/08/05 22:51:02]

Acknowledged.

+          RegisterBinding("webstore", context);

[not at google - send to devlin, 2014/08/05 22:43:39]

indentation

[sadrul, 2014/08/05 22:51:02]

Done.

 
       // ... and that the runtime API might be available if any extension can
       // connect to it.
@@ -1166,6 +1169,13 @@ bool Dispatcher::IsSandboxedPage(const GURL& url) const {
   return false;
 }
 
+bool Dispatcher::IsApiAvailable(const std::string& api_name,
+                                ScriptContext* context) {
+  return ExtensionAPI::GetSharedInstance()->IsAvailable(
+              api_name, context->extension(), context->context_type(),
+              context->GetURL()).is_available();
+}
+
 Feature::Context Dispatcher::ClassifyJavaScriptContext(
     const Extension* extension,
     int extension_group,