Retire ScopedObserver in /components/safe_browsing/content/password_protection.

ScopedObserver is being deprecated in favor of two new classes:
- base::ScopedObservation for observers that only ever observe
  a single source.
- base::ScopedMultiSourceObservation for observers that do or may
  observe more than a single source.

This CL was uploaded by git cl split.

R=bdea@chromium.org

Bug: 1145565
Change-Id: I852404bcc8df54aaa7273fd69ec47b80b0b44235
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2533155
Auto-Submit: Sigurður Ásgeirsson <siggi@chromium.org>
Reviewed-by: Bettina Dea <bdea@chromium.org>
Commit-Queue: Bettina Dea <bdea@chromium.org>
Cr-Commit-Position: refs/heads/master@{#826570}

components/safe_browsing/content/password_protection/password_protection_service.cc

@@ -61,7 +61,7 @@ PasswordProtectionService::PasswordProtectionService(
       url_loader_factory_(url_loader_factory) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   if (history_service)
-    history_service_observer_.Add(history_service);
+    history_service_observation_.Observe(history_service);
 
   common_spoofed_domains_ = {"login.live.com", "facebook.com", "box.com",
                              "google.com",     "paypal.com",   "apple.com",
@@ -72,7 +72,8 @@ PasswordProtectionService::PasswordProtectionService(
 PasswordProtectionService::~PasswordProtectionService() {
   tracker_.TryCancelAll();
   CancelPendingRequests();
-  history_service_observer_.RemoveAll();
+  if (history_service_observation_.IsObserving())
+    history_service_observation_.RemoveObservation();
   weak_factory_.InvalidateWeakPtrs();
 }
 
@@ -403,7 +404,8 @@ void PasswordProtectionService::OnURLsDeleted(
 
 void PasswordProtectionService::HistoryServiceBeingDeleted(
     history::HistoryService* history_service) {
-  history_service_observer_.RemoveAll();
+  DCHECK(history_service_observation_.IsObservingSource(history_service));
+  history_service_observation_.RemoveObservation();
 }
 
 std::unique_ptr<PasswordProtectionNavigationThrottle>

components/safe_browsing/content/password_protection/password_protection_service.h

@@ -14,7 +14,7 @@
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
-#include "base/scoped_observer.h"
+#include "base/scoped_observation.h"
 #include "base/task/cancelable_task_tracker.h"
 #include "base/values.h"
 #include "build/build_config.h"
@@ -522,8 +522,9 @@ class PasswordProtectionService : public history::HistoryServiceObserver {
   // dialog.
   std::list<std::string> common_spoofed_domains_;
 
-  ScopedObserver<history::HistoryService, history::HistoryServiceObserver>
-      history_service_observer_{this};
+  base::ScopedObservation<history::HistoryService,
+                          history::HistoryServiceObserver>
+      history_service_observation_{this};
 
   // Weakptr can only cancel task if it is posted to the same thread. Therefore,
   // we need CancelableTaskTracker to cancel tasks posted to IO thread.