Cleanup: remove not used forward declaration.

BUG=None

Review URL: https://codereview.chromium.org/340033002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@278079 0039d316-1c4b-4281-b951-d872f2087c98

content/renderer/screen_orientation/screen_orientation_dispatcher.h

@@ -14,10 +14,6 @@
 #include "third_party/WebKit/public/platform/WebScreenOrientationLockType.h"
 #include "third_party/WebKit/public/platform/WebScreenOrientationType.h"
 
-namespace blink {
-class WebScreenOrientationListener;
-}
-
 namespace content {
 
 class RenderFrame;