[Extensions] Expand bindings access checks

extensions/renderer/object_backed_native_handler.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "extensions/renderer/object_backed_native_handler.h"
 
 #include <stddef.h>
 
 #include "base/logging.h"
 #include "base/memory/linked_ptr.h"
@@ skipping 55 matching lines @@
   // don't inject many bindings into worker threads.
   // TODO(devlin): Figure out a way around this.
   if (content::WorkerThread::GetCurrentId() == 0) {
     ScriptContext* script_context =
         ScriptContextSet::GetContextByV8Context(context);
     v8::Local<v8::String> feature_name_string =
         feature_name_value->ToString(context).ToLocalChecked();
     std::string feature_name = *v8::String::Utf8Value(feature_name_string);
     // TODO(devlin): Eventually, we should fail if either script_context is null
     // or feature_name is empty.
-    if (script_context &&
-        !feature_name.empty() &&
-        !script_context->GetAvailability(feature_name).is_available()) {
-      return;
+    if (script_context && !feature_name.empty()) {
+      Feature::Availability availability =
+          script_context->GetAvailability(feature_name);
+      if (!availability.is_available()) {
+        DVLOG(1) << feature_name
+                 << " is not available: " << availability.message();
+        return;
+      }

[asargent_no_longer_on_chrome, 2016/04/11 17:30:14]

Did you intend for this to get checked in or were you just using this for local
testing/development?

[Devlin, 2016/04/13 19:51:26]

I wanted to check this one in (I think DVLOG is okay - locally I go straight to
LOG(WARNING) ;)).  It's useful information for debugging, and shouldn't clutter
the console, since it shouldn't likely be hit.

[asargent_no_longer_on_chrome, 2016/04/13 23:02:40]

Ok, just wasn't sure since a checked-in DVLOG is mostly only useful for local
builds. If this is something you foresee using a lot, I can see how having it
checked in is better than having to carry the patch around and always
re-applying it (eg via a git stash or whatever) and remembering to remove it
when uploading CLs. 

     }
   }
   // This CHECK is *important*. Otherwise, we'll go around happily executing
   // something random.  See crbug.com/548273.
   CHECK(handler_function_value->IsExternal());
   static_cast<HandlerFunction*>(
       handler_function_value.As<v8::External>()->Value())->Run(args);
 }
 
 void ObjectBackedNativeHandler::RouteFunction(
@@ skipping 95 matching lines @@
                                               v8::Local<v8::Object> obj,
                                               const char* key) {
   obj->DeletePrivate(context,
                      v8::Private::ForApi(
                          context->GetIsolate(),
                          v8::String::NewFromUtf8(context->GetIsolate(), key)))
       .FromJust();
 }
 
 }  // namespace extensions