Upstream Chrome on iOS source code [7/11].

ios/chrome/browser/ui/reader_mode/reader_mode_checker.h

+// Copyright 2015 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 IOS_CHROME_BROWSER_UI_READER_MODE_READER_MODE_CHECKER_H_
+#define IOS_CHROME_BROWSER_UI_READER_MODE_READER_MODE_CHECKER_H_
+
+#import <Foundation/Foundation.h>
+
+#include "base/memory/weak_ptr.h"
+#include "base/observer_list.h"
+#include "ios/web/public/web_state/web_state_observer.h"
+
+namespace web {
+class WebState;
+}
+
+class ReaderModeChecker;
+
+@class CRWJSInjectionReceiver;
+
+class ReaderModeCheckerObserver {
+ public:
+  explicit ReaderModeCheckerObserver(ReaderModeChecker* readerModeChecker);
+  virtual ~ReaderModeCheckerObserver();
+
+  // Called when the content of the page is known to be distillable.
+  virtual void PageIsDistillable() = 0;
+
+  // Invoked when the ReaderModeChecker is being destroyed. Gives subclasses a
+  // chance to cleanup.
+  virtual void ReaderModeCheckerDestroyed() {}
+
+ private:
+  ReaderModeChecker* readerModeChecker_;
+  DISALLOW_COPY_AND_ASSIGN(ReaderModeCheckerObserver);
+};
+
+// Checks if a page loaded in a container that allows javascript execution is
+// suitable for reader mode.
+class ReaderModeChecker : web::WebStateObserver {
+ public:
+  explicit ReaderModeChecker(web::WebState* web_state);
+  ~ReaderModeChecker() override;
+
+  // Returns the switch status of the current page.
+  bool CanSwitchToReaderMode();
+
+  // web::WebStateObserver.
+  void NavigationItemCommitted(
+      const web::LoadCommittedDetails& load_details) override;
+  void PageLoaded(
+      web::PageLoadCompletionStatus load_completion_status) override;
+  void WebStateDestroyed() override;
+
+  // Adds and removes observers for page navigation notifications. The order in
+  // which notifications are sent to observers is undefined. Clients must be
+  // sure to remove the observer before they go away.
+  void AddObserver(ReaderModeCheckerObserver* observer);
+  void RemoveObserver(ReaderModeCheckerObserver* observer);
+
+ private:
+  // Checks if the current webstate is distillable.
+  void CheckIsDistillable();
+  // Does a simple check, Just checking OpenGraph properties.
+  void CheckIsDistillableOG(CRWJSInjectionReceiver* receiver);
+  // Does a more involved check.
+  void CheckIsDistillableDetector(CRWJSInjectionReceiver* receiver);
+  // Stores if the current webstate URL is suitable for reader mode.
+  enum class Status;
+  Status is_distillable_;
+  // A list of observers notified when page state changes. Weak references.
+  base::ObserverList<ReaderModeCheckerObserver, true> observers_;
+  base::WeakPtrFactory<ReaderModeChecker> weak_factory_;
+  DISALLOW_COPY_AND_ASSIGN(ReaderModeChecker);
+};
+
+#endif  // IOS_CHROME_BROWSER_UI_READER_MODE_READER_MODE_CHECKER_H_