Move the event attach/detach logic on unload from event.js to

extensions/renderer/script_context.h

 // 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.
 
 #ifndef EXTENSIONS_RENDERER_SCRIPT_CONTEXT_H_
 #define EXTENSIONS_RENDERER_SCRIPT_CONTEXT_H_
 
 #include <string>
+#include <vector>
 
 #include "base/basictypes.h"
+#include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "extensions/common/features/feature.h"
 #include "extensions/common/permissions/api_permission_set.h"
 #include "extensions/renderer/module_system.h"
 #include "extensions/renderer/request_sender.h"
 #include "extensions/renderer/safe_builtins.h"
 #include "gin/runner.h"
 #include "url/gurl.h"
 #include "v8/include/v8.h"
 
@@ skipping 17 matching lines @@
                 const Extension* extension,
                 Feature::Context context_type,
                 const Extension* effective_extension,
                 Feature::Context effective_context_type);
   ~ScriptContext() override;
 
   // Clears the WebFrame for this contexts and invalidates the associated
   // ModuleSystem.
   void Invalidate();
 
+  // Registers |closure| to be run when this context is invalidated. Closures
+  // are run immediately when Invalidate() is called, not in a message loop.
+  void AddInvalidateObserver(const base::Closure& observer);

[Devlin, 2015/04/10 18:10:40]

nit: maybe Invalidated, or Invalidation?  InvalidateObserver sounds weird.

[not at google - send to devlin, 2015/04/10 18:39:02]

Invalidation it is.

+
   // Returns true if this context is still valid, false if it isn't.
   // A context becomes invalid via Invalidate().
-  bool is_valid() const { return !v8_context_.IsEmpty(); }
+  bool is_valid() const { return is_valid_; }
 
   v8::Handle<v8::Context> v8_context() const {
     return v8::Local<v8::Context>::New(isolate_, v8_context_);
   }
 
   const Extension* extension() const { return extension_.get(); }
 
   const Extension* effective_extension() const {
     return effective_extension_.get();
   }
@@ skipping 82 matching lines @@
 
   // Grants a set of content capabilities to this context.
   void SetContentCapabilities(const APIPermissionSet& permissions);
 
   // Indicates if this context has an effective API permission either by being
   // a context for an extension which has that permission, or by being a web
   // context which has been granted the corresponding capability by an
   // extension.
   bool HasAPIPermission(APIPermission::ID permission) const;
 
- protected:
-  // The v8 context the bindings are accessible to.
-  v8::Global<v8::Context> v8_context_;
-
  private:
   class Runner;
 
+  // Whether this context is valid.
+  bool is_valid_;
+
+  // The v8 context the bindings are accessible to.
+  v8::Global<v8::Context> v8_context_;
+
   // The WebFrame associated with this context. This can be NULL because this
   // object can outlive is destroyed asynchronously.
   blink::WebFrame* web_frame_;
 
   // The extension associated with this context, or NULL if there is none. This
   // might be a hosted app in the case that this context is hosting a web URL.
   scoped_refptr<const Extension> extension_;
 
   // The type of context.
   Feature::Context context_type_;
 
   // The effective extension associated with this context, or NULL if there is
   // none. This is different from the above extension if this context is in an
   // about:blank iframe for example.
   scoped_refptr<const Extension> effective_extension_;
 
   // The type of context.
   Feature::Context effective_context_type_;
 
   // Owns and structures the JS that is injected to set up extension bindings.
   scoped_ptr<ModuleSystem> module_system_;
 
   // Contains safe copies of builtin objects like Function.prototype.
   SafeBuiltins safe_builtins_;
 
   // The set of capabilities granted to this context by extensions.
   APIPermissionSet content_capabilities_;
 
+  // A list of base::Closure instances as an observer interface for
+  // invalidation.
+  std::vector<base::Closure> invalidate_observers_;
+
   v8::Isolate* isolate_;
 
   GURL url_;
 
   scoped_ptr<Runner> runner_;
 
   DISALLOW_COPY_AND_ASSIGN(ScriptContext);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_SCRIPT_CONTEXT_H_