Bug 1148012 - Expose run ID through nsIObjectLoadingContent.idl. r=josh,smaug.

The run ID for a plugin is retrieved and cached in the nsObjectLoadingContent
on plugin instantiation.

dom/plugins/base/nsNPAPIPluginInstance.cpp

@@ -1778,3 +1778,22 @@ nsNPAPIPluginInstance::GetContentsScaleFactor()
   }
   return scaleFactor;
 }
+
+nsresult
+nsNPAPIPluginInstance::GetRunID(uint32_t* aRunID)
+{
+  if (NS_WARN_IF(!aRunID)) {
+    return NS_ERROR_INVALID_POINTER;
+  }
+
+  if (NS_WARN_IF(!mPlugin)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  PluginLibrary* library = mPlugin->GetLibrary();
+  if (!library) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return library->GetRunID(aRunID);
+}