Implement the non-deprecated builder.

Any class inheriting `BrowserContextKeyedServiceFactory` should
implement either `BuildServiceInstanceForBrowserContext` or
`BuildServiceInstanceFor`. The second one was deprecated,
this CL replaces it with the first one.

Bug: 1396138
Change-Id: Iece7ebb503b4212f9d703fa8f26dcf88d4e84383
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4798401
Commit-Queue: Devlin Cronin <rdevlin.cronin@chromium.org>
Auto-Submit: Arthur Milchior <arthurmilchior@chromium.org>
Reviewed-by: Devlin Cronin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1187422}

extensions/browser/warning_service_factory.cc

@@ -35,9 +35,10 @@ WarningServiceFactory::WarningServiceFactory()
 WarningServiceFactory::~WarningServiceFactory() {
 }
 
-KeyedService* WarningServiceFactory::BuildServiceInstanceFor(
+std::unique_ptr<KeyedService>
+WarningServiceFactory::BuildServiceInstanceForBrowserContext(
     BrowserContext* context) const {
-  return new WarningService(context);
+  return std::make_unique<WarningService>(context);
 }
 
 BrowserContext* WarningServiceFactory::GetBrowserContextToUse(

extensions/browser/warning_service_factory.h

@@ -27,7 +27,7 @@ class WarningServiceFactory : public BrowserContextKeyedServiceFactory {
   ~WarningServiceFactory() override;
 
   // BrowserContextKeyedServiceFactory implementation
-  KeyedService* BuildServiceInstanceFor(
+  std::unique_ptr<KeyedService> BuildServiceInstanceForBrowserContext(
       content::BrowserContext* context) const override;
   content::BrowserContext* GetBrowserContextToUse(
       content::BrowserContext* context) const override;