chore: make BrowserObserver a CheckedObserver

refs: https://chromium-review.googlesource.com/c/chromium/src/+/1053338

atom/browser/api/atom_api_web_contents.h

@@ -15,6 +15,7 @@
 #include "atom/browser/common_web_contents_delegate.h"
 #include "atom/browser/ui/autofill_popup.h"
 #include "base/observer_list.h"
+#include "base/observer_list_types.h"
 #include "content/common/cursors/webcursor.h"
 #include "content/public/browser/keyboard_event_processing_result.h"
 #include "content/public/browser/web_contents.h"
@@ -60,10 +61,13 @@ namespace api {
 
 // Certain events are only in WebContentsDelegate, provide our own Observer to
 // dispatch those events.
-class ExtendedWebContentsObserver {
+class ExtendedWebContentsObserver : public base::CheckedObserver {
  public:
   virtual void OnCloseContents() {}
   virtual void OnRendererResponsive() {}
+
+ protected:
+  ~ExtendedWebContentsObserver() override {}
 };
 
 // Wrapper around the content::WebContents.

atom/browser/browser_observer.h

@@ -9,6 +9,7 @@
 
 #include "atom/browser/login_handler.h"
 #include "base/memory/scoped_refptr.h"
+#include "base/observer_list_types.h"
 #include "build/build_config.h"
 
 namespace base {
@@ -17,7 +18,7 @@ class DictionaryValue;
 
 namespace atom {
 
-class BrowserObserver {
+class BrowserObserver : public base::CheckedObserver {
  public:
   // The browser is about to close all windows.
   virtual void OnBeforeQuit(bool* prevent_default) {}
@@ -83,7 +84,7 @@ class BrowserObserver {
 #endif
 
  protected:
-  virtual ~BrowserObserver() {}
+  ~BrowserObserver() override {}
 };
 
 }  // namespace atom

atom/browser/native_window_observer.h

@@ -7,6 +7,7 @@
 
 #include <string>
 
+#include "base/observer_list_types.h"
 #include "base/strings/string16.h"
 #include "base/values.h"
 #include "ui/base/window_open_disposition.h"
@@ -22,9 +23,9 @@ class Rect;
 
 namespace atom {
 
-class NativeWindowObserver {
+class NativeWindowObserver : public base::CheckedObserver {
  public:
-  virtual ~NativeWindowObserver() {}
+  ~NativeWindowObserver() override {}
 
   // Called when the web page in window wants to create a popup window.
   virtual void WillCreatePopupWindow(const base::string16& frame_name,

atom/browser/ui/atom_menu_model.h

@@ -8,6 +8,7 @@
 #include <map>
 
 #include "base/observer_list.h"
+#include "base/observer_list_types.h"
 #include "ui/base/models/simple_menu_model.h"
 
 namespace atom {
@@ -33,9 +34,9 @@ class AtomMenuModel : public ui::SimpleMenuModel {
         ui::Accelerator* accelerator) const override;
   };
 
-  class Observer {
+  class Observer : public base::CheckedObserver {
    public:
-    virtual ~Observer() {}
+    ~Observer() override {}
 
     // Notifies the menu will open.
     virtual void OnMenuWillShow() {}

atom/browser/ui/tray_icon_observer.h

@@ -8,6 +8,8 @@
 #include <string>
 #include <vector>
 
+#include "base/observer_list_types.h"
+
 namespace gfx {
 class Rect;
 class Point;
@@ -15,7 +17,7 @@ class Point;
 
 namespace atom {
 
-class TrayIconObserver {
+class TrayIconObserver : public base::CheckedObserver {
  public:
   virtual void OnClicked(const gfx::Rect& bounds,
                          const gfx::Point& location,
@@ -36,7 +38,7 @@ class TrayIconObserver {
   virtual void OnMouseMoved(const gfx::Point& location, int modifiers) {}
 
  protected:
-  virtual ~TrayIconObserver() {}
+  ~TrayIconObserver() override {}
 };
 
 }  // namespace atom

atom/browser/ui/views/menu_delegate.h

@@ -70,7 +70,7 @@ class MenuDelegate : public views::MenuDelegate {
   views::MenuButton* button_to_open_ = nullptr;
   bool hold_first_switch_;
 
-  base::ObserverList<Observer> observers_;
+  base::ObserverList<Observer>::Unchecked observers_;
 
   DISALLOW_COPY_AND_ASSIGN(MenuDelegate);
 };

atom/browser/web_contents_zoom_controller.h

@@ -8,6 +8,7 @@
 #include <map>
 #include <string>
 
+#include "base/observer_list_types.h"
 #include "content/public/browser/host_zoom_map.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
@@ -19,7 +20,7 @@ class WebContentsZoomController
     : public content::WebContentsObserver,
       public content::WebContentsUserData<WebContentsZoomController> {
  public:
-  class Observer {
+  class Observer : public base::CheckedObserver {
    public:
     virtual void OnZoomLevelChanged(content::WebContents* web_contents,
                                     double level,
@@ -27,7 +28,7 @@ class WebContentsZoomController
     virtual void OnZoomControllerWebContentsDestroyed() {}
 
    protected:
-    virtual ~Observer() {}
+    ~Observer() override {}
   };
 
   // Defines how zoom changes are handled.

atom/browser/window_list_observer.h

@@ -5,11 +5,13 @@
 #ifndef ATOM_BROWSER_WINDOW_LIST_OBSERVER_H_
 #define ATOM_BROWSER_WINDOW_LIST_OBSERVER_H_
 
+#include "base/observer_list_types.h"
+
 namespace atom {
 
 class NativeWindow;
 
-class WindowListObserver {
+class WindowListObserver : public base::CheckedObserver {
  public:
   // Called immediately after a window is added to the list.
   virtual void OnWindowAdded(NativeWindow* window) {}
@@ -24,7 +26,7 @@ class WindowListObserver {
   virtual void OnWindowAllClosed() {}
 
  protected:
-  virtual ~WindowListObserver() {}
+  ~WindowListObserver() override {}
 };
 
 }  // namespace atom