cros: remove MagnificationManagerImpl

Changes:
This is a preparation CL. MagnificationManager could just be a concrete
class.

Bug: 817157
Test: compiles
Change-Id: If2d1e94e2679d220df142d115eaf36c93d456b6b
Reviewed-on: https://chromium-review.googlesource.com/1016321Reviewed-by: James Cook <jamescook@chromium.org>
Commit-Queue: Qiang Xu <warx@google.com>
Cr-Commit-Position: refs/heads/master@{#551779}

chrome/browser/chromeos/accessibility/magnification_manager.h

@@ -5,8 +5,12 @@
 #ifndef CHROME_BROWSER_CHROMEOS_ACCESSIBILITY_MAGNIFICATION_MANAGER_H_
 #define CHROME_BROWSER_CHROMEOS_ACCESSIBILITY_MAGNIFICATION_MANAGER_H_
 
-#include "chrome/browser/chromeos/accessibility/accessibility_manager.h"
+#include "base/macros.h"
+#include "components/user_manager/user_manager.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
 
+class PrefChangeRegistrar;
 class Profile;
 
 namespace chromeos {
@@ -19,7 +23,9 @@ namespace chromeos {
 //     desktop.
 //   - Watch change of the pref. When the pref changes, the setting of the
 //     magnifier will interlock with it.
-class MagnificationManager {
+class MagnificationManager
+    : public content::NotificationObserver,
+      public user_manager::UserManager::UserSessionStateObserver {
  public:
   // Creates an instance of MagnificationManager. This should be called once.
   static void Initialize();
@@ -31,21 +37,53 @@ class MagnificationManager {
   static MagnificationManager* Get();
 
   // Returns if the screen magnifier is enabled.
-  virtual bool IsMagnifierEnabled() const = 0;
+  bool IsMagnifierEnabled() const;
 
   // Enables the screen magnifier.
-  virtual void SetMagnifierEnabled(bool enabled) = 0;
+  void SetMagnifierEnabled(bool enabled);
 
   // Saves the magnifier scale to the pref.
-  virtual void SaveScreenMagnifierScale(double scale) = 0;
+  void SaveScreenMagnifierScale(double scale);
 
   // Loads the magnifier scale from the pref.
-  virtual double GetSavedScreenMagnifierScale() const = 0;
+  double GetSavedScreenMagnifierScale() const;
 
-  virtual void SetProfileForTest(Profile* profile) = 0;
+  void SetProfileForTest(Profile* profile);
 
- protected:
-  virtual ~MagnificationManager() {}
+ private:
+  MagnificationManager();
+  ~MagnificationManager() override;
+
+  // content::NotificationObserver overrides:
+  void Observe(int type,
+               const content::NotificationSource& source,
+               const content::NotificationDetails& details) override;
+
+  // user_manager::UserManager::UserSessionStateObserver overrides:
+  void ActiveUserChanged(const user_manager::User* active_user) override;
+
+  void SetProfile(Profile* profile);
+
+  void SetMagnifierEnabledInternal(bool enabled);
+  void SetMagnifierKeepFocusCenteredInternal(bool keep_focus_centered);
+  void SetMagnifierScaleInternal(double scale);
+  void UpdateMagnifierFromPrefs();
+
+  void MonitorFocusInPageChange();
+
+  Profile* profile_ = nullptr;
+
+  bool enabled_ = false;
+  bool keep_focus_centered_ = false;
+  double scale_ = 0.0;
+  bool observing_focus_change_in_page_ = false;
+
+  content::NotificationRegistrar registrar_;
+  std::unique_ptr<PrefChangeRegistrar> pref_change_registrar_;
+  std::unique_ptr<user_manager::ScopedUserSessionStateObserver>
+      session_state_observer_;
+
+  DISALLOW_COPY_AND_ASSIGN(MagnificationManager);
 };
 
 }  // namespace chromeos