Keyboard Lock Host implementation

components/keyboard_lock/page_observer.h

Index: components/keyboard_lock/page_observer.h
diff --git a/components/keyboard_lock/page_observer.h b/components/keyboard_lock/page_observer.h
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+// 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 COMPONENTS_KEYBOARD_LOCK_PAGE_OBSERVER_H_
+#define COMPONENTS_KEYBOARD_LOCK_PAGE_OBSERVER_H_
+
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
+#include "content/public/browser/web_contents_observer.h"
+
+namespace content {
+class NotificationDetails;
+class NotificationSource;
+class WebContents;
+}  // namespace content
+
+namespace keyboard_lock {
+
+class KeyHookActivator;
+class KeyHookActivatorCollection;
+
+// A PageObserver instance keeps a reference of a KeyHookActivator (usually a
+// KeyHookActivatorThreadProxy wrapped KeyHookStateKeeper instance) and a
+// WebContents. Once an interesting event, e.g. page taking or losing focus,
+// entering or exiting fullscreen, PageObserver calls
+// KeyHookActivator::Activate() or KeyHookActivator::Deactivate() functions.
+// A PageObserver instance has the same lifetime with its WebContents, it
+// deletes itself once WebContentsObserver::WebContentsDestroyed() is called.
+// This class must be instantiated in UI thread to ensure correct signals can be
+// received.
+class PageObserver final
+    : public content::NotificationObserver,
+      public content::WebContentsObserver {
+ public:
+  // |collection| must outlive current instance.
+  static void Observe(content::WebContents* web_contents,
+                      KeyHookActivatorCollection* collection);
+
+ private:
+  PageObserver(content::WebContents* web_contents,
+               KeyHookActivatorCollection* collection);
+  ~PageObserver() override;
+
+  // NotificationObserver implementations
+  void Observe(int type,
+               const content::NotificationSource& source,
+               const content::NotificationDetails& details) override;
+
+  // WebContentsObserver implementations
+  void OnWebContentsLostFocus() override;
+  void OnWebContentsFocused() override;
+  void WebContentsDestroyed() override;
+
+  void TriggerActivator();
+
+  bool is_fullscreen_ = false;
+  bool is_focused_ = false;
+  content::NotificationRegistrar registrar_;
+  KeyHookActivatorCollection* const collection_;
+};
+
+}  // namespace keyboard_lock
+
+#endif  // COMPONENTS_KEYBOARD_LOCK_PAGE_OBSERVER_H_