android: makes HistoryDeletionBridge properly remove observer

It looks like HistoryDeletionBridge is never destroyed. This ensures
the observer it adds to HistoryService is properly cleaned up.

BUG=1158388
TEST=none

Change-Id: Idc2f65405d277bb3b58fe3e821472f581d7df1fd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2613645Reviewed-by: Theresa  <twellington@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#840860}

chrome/browser/android/history/history_deletion_bridge.cc

@@ -36,22 +36,16 @@ history::DeletionInfo HistoryDeletionBridge::SanitizeDeletionInfo(
 }
 
 HistoryDeletionBridge::HistoryDeletionBridge(const JavaRef<jobject>& jobj)
-    : jobj_(ScopedJavaGlobalRef<jobject>(jobj)),
-      profile_(ProfileManager::GetLastUsedProfile()->GetOriginalProfile()) {
+    : jobj_(ScopedJavaGlobalRef<jobject>(jobj)) {
+  Profile* profile = ProfileManager::GetLastUsedProfile()->GetOriginalProfile();
   history::HistoryService* history_service =
-      HistoryServiceFactory::GetForProfile(profile_,
+      HistoryServiceFactory::GetForProfile(profile,
                                            ServiceAccessType::IMPLICIT_ACCESS);
   if (history_service)
-    history_service->AddObserver(this);
+    scoped_history_service_observer_.Observe(history_service);
 }
 
-HistoryDeletionBridge::~HistoryDeletionBridge() {
-  history::HistoryService* history_service =
-      HistoryServiceFactory::GetForProfile(profile_,
-                                           ServiceAccessType::IMPLICIT_ACCESS);
-  if (history_service)
-    history_service->RemoveObserver(this);
-}
+HistoryDeletionBridge::~HistoryDeletionBridge() = default;
 
 void HistoryDeletionBridge::OnURLsDeleted(
     history::HistoryService* history_service,
@@ -62,3 +56,8 @@ void HistoryDeletionBridge::OnURLsDeleted(
   Java_HistoryDeletionBridge_onURLsDeleted(
       env, jobj_, CreateHistoryDeletionInfo(env, &sanitized_info));
 }
+
+void HistoryDeletionBridge::HistoryServiceBeingDeleted(
+    history::HistoryService* history_service) {
+  scoped_history_service_observer_.Reset();
+}

chrome/browser/android/history/history_deletion_bridge.h

@@ -6,6 +6,8 @@
 #define CHROME_BROWSER_ANDROID_HISTORY_HISTORY_DELETION_BRIDGE_H_
 
 #include "base/macros.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/history_types.h"
 
@@ -13,8 +15,6 @@ namespace history {
 class HistoryService;
 }  // namespace history
 
-class Profile;
-
 // Native counterpart of HistoryDeletionBridge.java. Receives history deletion
 // events that originate in native code and forwards them to Java.
 class HistoryDeletionBridge : public history::HistoryServiceObserver {
@@ -24,6 +24,8 @@ class HistoryDeletionBridge : public history::HistoryServiceObserver {
   // history::HistoryServiceObserver.
   void OnURLsDeleted(history::HistoryService* history_service,
                      const history::DeletionInfo& deletion_info) override;
+  void HistoryServiceBeingDeleted(
+      history::HistoryService* history_service) override;
 
   // Sanitize the DeletionInfo of empty/invalid urls before passing to java.
   // Fix for empty java strings being passed to the content capture service
@@ -37,7 +39,9 @@ class HistoryDeletionBridge : public history::HistoryServiceObserver {
   // Reference to the Java half of this bridge. Always valid.
   base::android::ScopedJavaGlobalRef<jobject> jobj_;
 
-  Profile* profile_;
+  base::ScopedObservation<history::HistoryService,
+                          history::HistoryServiceObserver>
+      scoped_history_service_observer_{this};
 
   DISALLOW_COPY_AND_ASSIGN(HistoryDeletionBridge);
 };