Move lazy event dispatching code out of EventRouter.

extensions/browser/lazy_context_id.h

+// Copyright 2017 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_BROWSER_LAZY_CONTEXT_ID_H_
+#define EXTENSIONS_BROWSER_LAZY_CONTEXT_ID_H_
+
+#include "extensions/common/extension_id.h"
+#include "url/gurl.h"
+
+namespace content {
+class BrowserContext;
+}
+
+namespace extensions {
+class LazyBackgroundTaskQueue;
+
+class LazyContextId {
+ public:
+  enum class Type {
+    kEventPage,
+  };
+
+  // An event page (lazy background) context.
+  LazyContextId(content::BrowserContext* context,
+                const ExtensionId& extension_id);
+  // TODO(lazyboy): Service worker context.
+
+  bool is_for_event_page() const { return type_ == Type::kEventPage; }
+
+  content::BrowserContext* browser_context() const { return context_; }
+  void set_browser_context(content::BrowserContext* context) {
+    context_ = context;
+  }
+
+  const ExtensionId& extension_id() const { return extension_id_; }
+
+  // TODO(lazyboy): Use a generic interface to support service workers.
+  LazyBackgroundTaskQueue* GetTaskQueue();
+
+ private:
+  const Type type_;
+  content::BrowserContext* context_;
+  const ExtensionId extension_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(LazyContextId);
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_BROWSER_LAZY_CONTEXT_ID_H_