Convert //chromecast from scoped_ptr to std::unique_ptr

chromecast/browser/cast_browser_context.cc

Index: chromecast/browser/cast_browser_context.cc
diff --git a/chromecast/browser/cast_browser_context.cc b/chromecast/browser/cast_browser_context.cc
index b229b66416aa388eb3736fd37dde39a80f53359a..bba02becc1c66346c1e3e9515bfeacaf685b0904 100644
--- a/chromecast/browser/cast_browser_context.cc
+++ b/chromecast/browser/cast_browser_context.cc
@@ -80,7 +80,7 @@ void CastBrowserContext::InitWhileIOAllowed() {
   BrowserContext::Initialize(this, path_);
 }
 
-scoped_ptr<content::ZoomLevelDelegate>
+std::unique_ptr<content::ZoomLevelDelegate>
 CastBrowserContext::CreateZoomLevelDelegate(
     const base::FilePath& partition_path) {
   return nullptr;