Add UseCounters for ViewportAPI

third_party/WebKit/Source/core/core.gypi

 {
     'includes': [
         'core_generated.gypi',
     ],
     'variables': {
         # Files for which bindings (.cpp and .h files) will be generated
         'core_idl_files': [
             'animation/KeyframeEffect.idl',
             'animation/EffectModel.idl',
             'animation/AnimationEffectReadOnly.idl',
@@ skipping 2815 matching lines @@
             'events/TouchEvent.cpp',
             'events/TouchEvent.h',
             'events/TouchEventContext.cpp',
             'events/TouchEventContext.h',
             'events/TransitionEvent.cpp',
             'events/TransitionEvent.h',
             'events/TreeScopeEventContext.cpp',
             'events/TreeScopeEventContext.h',
             'events/UIEvent.cpp',
             'events/UIEventWithKeyState.cpp',
+            'events/VisualViewportResizeEvent.cpp',
+            'events/VisualViewportResizeEvent.h',
+            'events/VisualViewportScrollEvent.cpp',
+            'events/VisualViewportScrollEvent.h',
             'events/WheelEvent.cpp',
             'events/WheelEvent.h',
             'events/WindowEventContext.cpp',
             'events/WindowEventContext.h',
             'input/EventHandler.cpp',
             'input/EventHandler.h',
             'input/GestureManager.cpp',
             'input/GestureManager.h',
             'input/InputDeviceCapabilities.cpp',
             'input/InputDeviceCapabilities.h',
@@ skipping 1377 matching lines @@
             'testing/PrivateScriptTestTest.cpp',
             'timing/MemoryInfoTest.cpp',
             'timing/PerformanceBaseTest.cpp',
             'timing/PerformanceObserverTest.cpp',
             'workers/WorkerThreadTest.cpp',
             'workers/WorkerThreadTestHelper.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }