Notify in console when an API fails because it needs to be invoked on user action.

Source/core/dom/Fullscreen.cpp

Index: Source/core/dom/Fullscreen.cpp
diff --git a/Source/core/dom/Fullscreen.cpp b/Source/core/dom/Fullscreen.cpp
index 64b67a512ecf0eaffa02f3a1ab79bd769c43df31..f30be0ab693abb9241a62329eeca85541592b069 100644
--- a/Source/core/dom/Fullscreen.cpp
+++ b/Source/core/dom/Fullscreen.cpp
@@ -231,8 +231,12 @@ void Fullscreen::requestFullscreen(Element& element, RequestType requestType)
         //   An algorithm is allowed to show a pop-up if, in the task in which the algorithm is running, either:
         //   - an activation behavior is currently being processed whose click event was trusted, or
         //   - the event listener for a trusted click event is being handled.
-        if (!UserGestureIndicator::processingUserGesture())
+        if (!UserGestureIndicator::processingUserGesture()) {
+            document()->executionContext()->addConsoleMessage(ConsoleMessage::create(JSMessageSource, WarningMessageLevel,
+                "Permission denied for requestFullScreen() as it was invoked by script, without any user interaction involved!"));

[meacer, 2014/09/24 17:59:21]

The message sounds a bit verbose. You might want to make this look like similar
messages:
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/renderer/ex...

"requestFullScreen can only be initiated by a user gesture"

[Mayur Kankanwadi, 2014/09/25 06:43:01]

Done.

+
             break;
+        }
 
         // Fullscreen is not supported.
         if (!fullscreenIsSupported(element.document(), element))