Use the correct v8 context for conversions when calling into the plugin from JS

content/renderer/pepper/pepper_plugin_instance_impl.h

Index: content/renderer/pepper/pepper_plugin_instance_impl.h
diff --git a/content/renderer/pepper/pepper_plugin_instance_impl.h b/content/renderer/pepper/pepper_plugin_instance_impl.h
index 7823627b2cab236927363b7cd02d00d14e7abb79..bc4ee1e9c1df4ead2ab009fdccb34b6e0cc4e2d0 100644
--- a/content/renderer/pepper/pepper_plugin_instance_impl.h
+++ b/content/renderer/pepper/pepper_plugin_instance_impl.h
@@ -149,8 +149,12 @@ class CONTENT_EXPORT PepperPluginInstanceImpl
   // the plugin being destroyed.
   void MessageChannelDestroyed();
 
-  // Return the v8 context that the plugin is in.
-  v8::Local<v8::Context> GetContext();
+  // Return the v8 context for the frame that the plugin is contained in. Care
+  // should be taken to use the correct context for plugin<->JS interactions.
+  // In cases where JS calls into the plugin, the caller's context should
+  // typically be used. When calling from the plugin into JS, this context
+  // should typically used.
+  v8::Local<v8::Context> GetMainWorldContext();
 
   // Does some pre-destructor cleanup on the instance. This is necessary
   // because some cleanup depends on the plugin instance still existing (like