Retire ScopedObserver in /components/history.

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=sky@chromium.org

Bug: 1145565
Change-Id: Ieb10240f6035314a206ea814709c43c1c739ac7d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2532954
Commit-Queue: Sigurður Ásgeirsson <siggi@chromium.org>
Auto-Submit: Sigurður Ásgeirsson <siggi@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#826827}

components/history/core/browser/browsing_history_service.cc

@@ -173,12 +173,12 @@ BrowsingHistoryService::BrowsingHistoryService(
 
   // Get notifications when history is cleared.
   if (local_history_)
-    history_service_observer_.Add(local_history_);
+    history_service_observation_.Observe(local_history_);
 
   // Get notifications when web history is deleted.
   WebHistoryService* web_history = driver_->GetWebHistoryService();
   if (web_history) {
-    web_history_service_observer_.Add(web_history);
+    web_history_service_observation_.Observe(web_history);
   } else if (sync_service_) {
     // If |web_history| is not available, it means that history sync is
     // disabled. If |sync_service_| is not null, it means that syncing is
@@ -187,7 +187,7 @@ BrowsingHistoryService::BrowsingHistoryService(
     // observing. This is okay because sync will never start for us, for example
     // it may be disabled by flag or we're part of an incognito/guest mode
     // window.
-    sync_service_observer_.Add(sync_service_);
+    sync_service_observation_.Observe(sync_service_);
   }
 }
 
@@ -201,9 +201,9 @@ void BrowsingHistoryService::OnStateChanged(syncer::SyncService* sync) {
   // This method should not be called after we already added the observer.
   WebHistoryService* web_history = driver_->GetWebHistoryService();
   if (web_history) {
-    DCHECK(!web_history_service_observer_.IsObserving(web_history));
-    web_history_service_observer_.Add(web_history);
-    sync_service_observer_.RemoveAll();
+    DCHECK(!web_history_service_observation_.IsObserving());
+    web_history_service_observation_.Observe(web_history);
+    sync_service_observation_.RemoveObservation();
   }
 }
 

components/history/core/browser/browsing_history_service.h

@@ -17,7 +17,7 @@
 #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/strings/string16.h"
 #include "base/task/cancelable_task_tracker.h"
 #include "base/time/clock.h"
@@ -227,16 +227,16 @@ class BrowsingHistoryService : public HistoryServiceObserver,
   std::unique_ptr<base::OneShotTimer> web_history_timer_;
 
   // HistoryService (local history) observer.
-  ScopedObserver<HistoryService, HistoryServiceObserver>
-      history_service_observer_{this};
+  base::ScopedObservation<HistoryService, HistoryServiceObserver>
+      history_service_observation_{this};
 
   // WebHistoryService (synced history) observer.
-  ScopedObserver<WebHistoryService, WebHistoryServiceObserver>
-      web_history_service_observer_{this};
+  base::ScopedObservation<WebHistoryService, WebHistoryServiceObserver>
+      web_history_service_observation_{this};
 
   // SyncService observer listens to late initialization of history sync.
-  ScopedObserver<syncer::SyncService, syncer::SyncServiceObserver>
-      sync_service_observer_{this};
+  base::ScopedObservation<syncer::SyncService, syncer::SyncServiceObserver>
+      sync_service_observation_{this};
 
   // Whether the last call to Web History returned synced results.
   bool has_synced_results_ = false;

components/history/core/browser/expire_history_backend_unittest.cc

@@ -17,7 +17,7 @@
 #include "base/files/file_util.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/run_loop.h"
-#include "base/scoped_observer.h"
+#include "base/scoped_observation.h"
 #include "base/stl_util.h"
 #include "base/strings/string16.h"
 #include "base/strings/utf_string_conversions.h"

components/history/core/browser/in_memory_history_backend.cc

@@ -27,7 +27,7 @@ void InMemoryHistoryBackend::AttachToHistoryService(
     HistoryService* history_service) {
   DCHECK(db_);
   DCHECK(history_service);
-  history_service_observer_.Add(history_service);
+  history_service_observation_.Observe(history_service);
 }
 
 void InMemoryHistoryBackend::DeleteAllSearchTermsForKeyword(

components/history/core/browser/in_memory_history_backend.h

@@ -25,7 +25,7 @@
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
-#include "base/scoped_observer.h"
+#include "base/scoped_observation.h"
 #include "components/history/core/browser/history_service.h"
 #include "components/history/core/browser/history_service_observer.h"
 #include "components/history/core/browser/keyword_id.h"
@@ -91,8 +91,8 @@ class InMemoryHistoryBackend : public HistoryServiceObserver {
 
   std::unique_ptr<InMemoryDatabase> db_;
 
-  ScopedObserver<HistoryService, HistoryServiceObserver>
-      history_service_observer_{this};
+  base::ScopedObservation<HistoryService, HistoryServiceObserver>
+      history_service_observation_{this};
 
   DISALLOW_COPY_AND_ASSIGN(InMemoryHistoryBackend);
 };

components/history/core/browser/top_sites_impl.cc

@@ -214,7 +214,8 @@ void TopSitesImpl::OnNavigationCommitted(const GURL& url) {
 
 void TopSitesImpl::ShutdownOnUIThread() {
   history_service_ = nullptr;
-  history_service_observer_.RemoveAll();
+  if (history_service_observation_.IsObserving())
+    history_service_observation_.RemoveObservation();
   // Cancel all requests so that the service doesn't callback to us after we've
   // invoked Shutdown (this could happen if we have a pending request and
   // Shutdown is invoked).
@@ -398,7 +399,7 @@ void TopSitesImpl::MoveStateToLoaded() {
     std::move(callback).Run(urls);
 
   if (history_service_)
-    history_service_observer_.Add(history_service_);
+    history_service_observation_.Observe(history_service_);
 
   NotifyTopSitesLoaded();
 }

components/history/core/browser/top_sites_impl.h

@@ -14,7 +14,7 @@
 #include "base/callback.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
-#include "base/scoped_observer.h"
+#include "base/scoped_observation.h"
 #include "base/synchronization/lock.h"
 #include "base/task/cancelable_task_tracker.h"
 #include "base/threading/thread_checker.h"
@@ -210,8 +210,8 @@ class TopSitesImpl : public TopSites, public HistoryServiceObserver {
   // The histogram should only be recorded once for each Chrome execution.
   static bool histogram_recorded_;
 
-  ScopedObserver<HistoryService, HistoryServiceObserver>
-      history_service_observer_{this};
+  base::ScopedObservation<HistoryService, HistoryServiceObserver>
+      history_service_observation_{this};
 
   DISALLOW_COPY_AND_ASSIGN(TopSitesImpl);
 };