[Blink>Fullscreen] Add UseCounter for fullscreen on orientation change

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 c168a417617edd87a6e25b1ce2aabfeda4e6ecce..ce9f4d9eb6ad74df28a9132e97f666b25422695e 100644
--- a/third_party/WebKit/Source/core/dom/Fullscreen.cpp
+++ b/third_party/WebKit/Source/core/dom/Fullscreen.cpp
@@ -87,8 +87,11 @@ bool allowedToRequestFullscreen(Document& document) {
     return true;
 
   //  The algorithm is triggered by a user generated orientation change.
-  if (ScopedOrientationChangeIndicator::processingOrientationChange())
+  if (ScopedOrientationChangeIndicator::processingOrientationChange()) {
+    UseCounter::count(document,
+                      UseCounter::FullscreenAllowedByOrientationChange);
     return true;
+  }
 
   String message = ExceptionMessages::failedToExecute(
       "requestFullscreen", "Element",