Add a requestFullscreen variant with a default (prefixed) type

third_party/WebKit/Source/modules/vr/VRDisplay.cpp

Index: third_party/WebKit/Source/modules/vr/VRDisplay.cpp
diff --git a/third_party/WebKit/Source/modules/vr/VRDisplay.cpp b/third_party/WebKit/Source/modules/vr/VRDisplay.cpp
index 4558f62e6091fb92ba3136db4ff2bfcd45031fbc..debe0fbb00e63bdbc73428496e02b74aa827bdb2 100644
--- a/third_party/WebKit/Source/modules/vr/VRDisplay.cpp
+++ b/third_party/WebKit/Source/modules/vr/VRDisplay.cpp
@@ -490,7 +490,7 @@ void VRDisplay::beginPresent() {
           new UserGestureIndicator(DocumentUserGestureToken::create(
               doc, UserGestureToken::Status::PossiblyExistingGesture)));
     }
-    Fullscreen::requestFullscreen(*canvas, Fullscreen::UnprefixedRequest);
+    Fullscreen::requestFullscreen(*canvas);
 
     // Check to see if the canvas is still the current fullscreen
     // element once every 2 seconds.
@@ -728,7 +728,7 @@ void VRDisplay::onFullscreenCheck(TimerBase*) {
           new UserGestureIndicator(DocumentUserGestureToken::create(
               doc, UserGestureToken::Status::PossiblyExistingGesture)));
     }
-    Fullscreen::requestFullscreen(*canvas, Fullscreen::UnprefixedRequest);
+    Fullscreen::requestFullscreen(*canvas);
   }
 }