Fix bug where content scripts can get GC'd if they don't attach

chrome/renderer/extensions/bindings_utils.h

 // Copyright (c) 2009 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.
 
 #ifndef CHROME_RENDERER_EXTENSIONS_BINDINGS_UTILS_H_
 #define CHROME_RENDERER_EXTENSIONS_BINDINGS_UTILS_H_
 
 #include "app/resource_bundle.h"
 #include "base/linked_ptr.h"
 #include "base/singleton.h"
@@ skipping 50 matching lines @@
   std::string extension_id;  // empty if the context is not an extension
 
   // If this context is a content script, parent will be the frame that it
   // was injected in.  This is empty if the context is not a content script.
   v8::Persistent<v8::Context> parent_context;
 
   // The RenderView that this context belongs to.  This is not guaranteed to be
   // a valid pointer, and is used for comparisons only.  Do not dereference.
   RenderView* render_view;
 
+  // A count of the number of events that are listening in this context. When
+  // this is zero, |context| will be a weak handle.
+  int num_connected_events;
+
   ContextInfo(v8::Persistent<v8::Context> context,
               const std::string& extension_id,
               v8::Persistent<v8::Context> parent_context,
               RenderView* render_view)
       : context(context), extension_id(extension_id),
-        parent_context(parent_context), render_view(render_view) {}
+        parent_context(parent_context), render_view(render_view),
+        num_connected_events(0) {}
 };
 typedef std::list< linked_ptr<ContextInfo> > ContextList;
 
 // Returns a mutable reference to the ContextList.
 ContextList& GetContexts();
 
 // Returns a (copied) list of contexts that have the given extension_id.
 ContextList GetContextsForExtension(const std::string& extension_id);
 
 // Returns the ContextInfo item that has the given context.
 ContextList::iterator FindContext(v8::Handle<v8::Context> context);
 
+// Returns the ContextInfo for the current v8 context.
+ContextInfo* GetInfoForCurrentContext();
+
 // Contains info relevant to a pending API request.
 struct PendingRequest {
  public :
   PendingRequest(v8::Persistent<v8::Context> context, const std::string& name)
       : context(context), name(name) {
   }
   v8::Persistent<v8::Context> context;
   std::string name;
 };
 typedef std::map<int, linked_ptr<PendingRequest> > PendingRequestMap;
@@ skipping 10 matching lines @@
 // be a sub-property like "Port.dispatchOnMessage". Returns the result of 
 // the function call. If an exception is thrown an empty Handle will be
 // returned.
 v8::Handle<v8::Value> CallFunctionInContext(v8::Handle<v8::Context> context,
     const std::string& function_name, int argc,
     v8::Handle<v8::Value>* argv);
 
 }  // namespace bindings_utils
 
 #endif  // CHROME_RENDERER_EXTENSIONS_BINDINGS_UTILS_H_