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

chrome/renderer/extensions/event_bindings.cc

Index: chrome/renderer/extensions/event_bindings.cc
diff --git a/chrome/renderer/extensions/event_bindings.cc b/chrome/renderer/extensions/event_bindings.cc
index 416ab2cf5dd4ec0f7932185c2ecabf74f03d5c02..1d7feb9086bd08fabfe5750c0966e32a939c3175 100644
--- a/chrome/renderer/extensions/event_bindings.cc
+++ b/chrome/renderer/extensions/event_bindings.cc
@@ -22,12 +22,16 @@ using bindings_utils::CallFunctionInContext;
 using bindings_utils::ContextInfo;
 using bindings_utils::ContextList;
 using bindings_utils::GetContexts;
+using bindings_utils::GetInfoForCurrentContext;
 using bindings_utils::GetStringResource;
 using bindings_utils::ExtensionBase;
 using bindings_utils::GetPendingRequestMap;
 using bindings_utils::PendingRequestMap;
 using WebKit::WebFrame;
 
+static void ContextWeakReferenceCallback(v8::Persistent<v8::Value> context,
+                                         void*);
+
 namespace {
 
 // Keep a local cache of RenderThread so that we can mock it out for unit tests.
@@ -79,11 +83,7 @@ class ExtensionImpl : public ExtensionBase {
       std::string event_name(*v8::String::AsciiValue(args[0]));
       bool has_permission =
           ExtensionProcessBindings::CurrentContextHasPermission(event_name);
-#if EXTENSION_TIME_TO_BREAK_API
       bool allow_api = has_permission;

[Matt Perry, 2009/09/14 18:07:47]

may as well remove this and use has_permission directly

-#else
-      bool allow_api = true;
-#endif
 
       // Increment the count even if the caller doesn't have permission, so that
       // refcounts stay balanced.
@@ -92,6 +92,10 @@ class ExtensionImpl : public ExtensionBase {
             new ViewHostMsg_ExtensionAddListener(event_name));
       }
 
+      ContextInfo* current_context_info = GetInfoForCurrentContext();
+      if (++current_context_info->num_connected_events == 1)
+        current_context_info->context.ClearWeak();
+
       if (!has_permission) {
         return ExtensionProcessBindings::ThrowPermissionDeniedException(
             event_name);
@@ -112,6 +116,13 @@ class ExtensionImpl : public ExtensionBase {
         EventBindings::GetRenderThread()->Send(
           new ViewHostMsg_ExtensionRemoveListener(event_name));
       }
+
+      ContextInfo* current_context_info = GetInfoForCurrentContext();
+      if (current_context_info &&

[Matt Perry, 2009/09/14 18:07:47]

why the NULL-check here but not in AttachEvent?

+          --current_context_info->num_connected_events == 0) {
+        current_context_info->context.MakeWeak(NULL,
+            &ContextWeakReferenceCallback);
+      }
     }
 
     return v8::Undefined();