Lazy load chrome.* APIs

chrome/renderer/extensions/object_backed_native_handler.h

+// Copyright (c) 2012 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_OBJECT_BACKED_NATIVE_HANDLER_H_
+#define CHROME_RENDERER_EXTENSIONS_OBJECT_BACKED_NATIVE_HANDLER_H_
+
+#include <string>
+#include <vector>
+
+#include "base/bind.h"
+#include "base/memory/linked_ptr.h"
+#include "chrome/renderer/extensions/native_handler.h"
+#include "v8/include/v8.h"
+
+namespace extensions {
+
+// An ObjectBackedNativeHandler is a factory for JS objects with functions on
+// them that map to native C++ functions. Subclasses should call RouteFunction()
+// in their constructor to define functions on the created JS objects.
+class ObjectBackedNativeHandler : public NativeHandler {
+ public:
+  explicit ObjectBackedNativeHandler(v8::Handle<v8::Context> context);
+  virtual ~ObjectBackedNativeHandler();
+
+  // Create an object with bindings to the native functions defined through
+  // RouteFunction().
+  virtual v8::Handle<v8::Object> NewInstance() OVERRIDE;
+
+ protected:
+  typedef v8::Handle<v8::Value> (*HandlerFunc)(const v8::Arguments&);
+  typedef base::Callback<v8::Handle<v8::Value>(const v8::Arguments&)>
+      HandlerFunction;
+
+  // Installs a new 'route' from |name| to |handler_function|. This means that
+  // NewInstance()s of this ObjectBackedNativeHandler will have a property
+  // |name| which will be handled by |handler_function|.
+  void RouteFunction(const std::string& name,
+                     const HandlerFunction& handler_function);
+
+  void RouteStaticFunction(const std::string& name,
+                           const HandlerFunc handler_func);
+
+  // Invalidate this object so it cannot be used any more. This is needed
+  // because it's possible for this to outlive |v8_context_|. Invalidate must
+  // be called before this happens.
+  //
+  // Subclasses may override to invalidate their own V8 state, but always
+  // call superclass eventually.
+  //
+  // This must be idempotent. Returns true if it was the first time this was
+  // called, false otherwise.
+  virtual bool Invalidate();
+
+  v8::Handle<v8::Context> v8_context() { return v8_context_; }
+
+ private:
+  static v8::Handle<v8::Value> Router(const v8::Arguments& args);
+
+  std::vector<linked_ptr<HandlerFunction> > handler_functions_;
+  v8::Handle<v8::Context> v8_context_;
+  v8::Persistent<v8::ObjectTemplate> object_template_;
+  bool is_valid_;
+
+  DISALLOW_COPY_AND_ASSIGN(ObjectBackedNativeHandler);
+};
+
+}  // extensions
+
+#endif  // CHROME_RENDERER_EXTENSIONS_OBJECT_BACKED_NATIVE_HANDLER_H_