Make content::FeaturePolicy implement WebFeaturePolicy, and use it in blink code

third_party/WebKit/Source/core/dom/Fullscreen.cpp

Index: third_party/WebKit/Source/core/dom/Fullscreen.cpp
diff --git a/third_party/WebKit/Source/core/dom/Fullscreen.cpp b/third_party/WebKit/Source/core/dom/Fullscreen.cpp
index 7d3ee2056cb1247c5be7ab1cd725bc0787e2b8f0..ddb8d21e7349a0e10c4444521e10de89227cb667 100644
--- a/third_party/WebKit/Source/core/dom/Fullscreen.cpp
+++ b/third_party/WebKit/Source/core/dom/Fullscreen.cpp
@@ -50,6 +50,7 @@
 #include "core/svg/SVGSVGElement.h"
 #include "platform/ScopedOrientationChangeIndicator.h"
 #include "platform/UserGestureIndicator.h"
+#include "public/platform/Platform.h"
 
 namespace blink {
 
@@ -86,8 +87,7 @@ bool allowedToUseFullscreen(const Frame* frame) {
 
   // 1. If FP, by itself, enables fullscreen in this document, then fullscreen
   // is allowed.
-  if (frame->securityContext()->getFeaturePolicy()->isFeatureEnabled(
-          kFullscreenFeature)) {
+  if (isFeatureEnabledInFrame(WebFeaturePolicyFeature::Fullscreen, frame)) {
     return true;
   }