[Sync] Migrate SyncInternalsMessageHandler off CallJavascriptFunctionUnsafe.

components/sync/driver/sync_service_base.cc

Index: components/sync/driver/sync_service_base.cc
diff --git a/components/sync/driver/sync_service_base.cc b/components/sync/driver/sync_service_base.cc
index 39e252c8fb91cc3cc71f1b6d8339f8b3d699c621..a98b3cf25f2027b1b65d9cd7411eff045be95c9b 100644
--- a/components/sync/driver/sync_service_base.cc
+++ b/components/sync/driver/sync_service_base.cc
@@ -78,6 +78,16 @@ void SyncServiceBase::RemoveObserver(SyncServiceObserver* observer) {
   observers_.RemoveObserver(observer);
 }
 
+bool SyncServiceBase::HasObserver(const SyncServiceObserver* observer) const {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  return observers_.HasObserver(observer);
+}
+
+SigninManagerBase* SyncServiceBase::signin() const {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  return signin_ ? signin_->GetOriginal() : nullptr;
+}
+
 // static
 base::FilePath SyncServiceBase::FormatSyncDataPath(
     const base::FilePath& base_directory) {
@@ -91,11 +101,6 @@ base::FilePath SyncServiceBase::FormatSharedModelTypeStorePath(
       .Append(base::FilePath(kLevelDBFolderName));
 }
 
-bool SyncServiceBase::HasObserver(const SyncServiceObserver* observer) const {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  return observers_.HasObserver(observer);
-}
-
 void SyncServiceBase::NotifyObservers() {
   for (auto& observer : observers_) {
     observer.OnStateChanged(this);