Chrome cleaner: make Observer a CheckedObserver

Bug: 1087263
Change-Id: I2125c7072fcc9295749ff04f514e1b13d8754143
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2355905Reviewed-by: Joe Mason <joenotcharles@chromium.org>
Commit-Queue: Rainhard Findling <rainhard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#798637}

chrome/browser/safe_browsing/chrome_cleaner/chrome_cleaner_controller_impl_win.h

@@ -145,7 +145,7 @@ class ChromeCleanerControllerImpl : public ChromeCleanerController {
   base::Time time_scanning_started_;
   base::Time time_cleanup_started_;
 
-  base::ObserverList<Observer>::Unchecked observer_list_;
+  base::ObserverList<Observer> observer_list_;
 
   // Mutex that guards |pending_invocation_type_|,
   // |on_demand_sw_reporter_fetcher_| and |cached_reporter_invocations_|.

chrome/browser/safe_browsing/chrome_cleaner/chrome_cleaner_controller_win.h

@@ -11,6 +11,7 @@
 #include "base/callback.h"
 #include "base/files/file_path.h"
 #include "base/macros.h"
+#include "base/observer_list.h"
 #include "chrome/browser/safe_browsing/chrome_cleaner/chrome_cleaner_scanner_results_win.h"
 #include "chrome/browser/safe_browsing/chrome_cleaner/sw_reporter_invocation_win.h"
 
@@ -97,7 +98,7 @@ class ChromeCleanerController {
     kDismissed,
   };
 
-  class Observer {
+  class Observer : public base::CheckedObserver {
    public:
     virtual void OnIdle(IdleReason idle_reason) {}
     virtual void OnReporterRunning() {}
@@ -110,9 +111,6 @@ class ChromeCleanerController {
         const ChromeCleanerScannerResults& scanner_results) {}
     virtual void OnRebootRequired() {}
     virtual void OnRebootFailed() {}
-
-   protected:
-    virtual ~Observer() = default;
   };
 
   // Returns the global controller object.