Remove PlatformEvent it is no longer used.

third_party/WebKit/Source/core/input/GestureManager.cpp

Index: third_party/WebKit/Source/core/input/GestureManager.cpp
diff --git a/third_party/WebKit/Source/core/input/GestureManager.cpp b/third_party/WebKit/Source/core/input/GestureManager.cpp
index 5646057fc0f7b85e343118b334a0532e3e5b79c7..1c111cf0f44990d63d4e34365054e4c994626240 100644
--- a/third_party/WebKit/Source/core/input/GestureManager.cpp
+++ b/third_party/WebKit/Source/core/input/GestureManager.cpp
@@ -154,7 +154,7 @@ WebInputEventResult GestureManager::handleGestureTap(
         WebInputEvent::MouseMove, gestureEvent,
         WebPointerProperties::Button::NoButton,
         /* clickCount */ 0,
-        static_cast<PlatformEvent::Modifiers>(
+        static_cast<WebInputEvent::Modifiers>(
             modifiers | WebInputEvent::Modifiers::IsCompatibilityEventForTouch),
         gestureEvent.timeStampSeconds());
     m_mouseEventManager->setMousePositionAndDispatchMouseEvent(
@@ -196,7 +196,7 @@ WebInputEventResult GestureManager::handleGestureTap(
   WebMouseEvent fakeMouseDown(
       WebInputEvent::MouseDown, gestureEvent,
       WebPointerProperties::Button::Left, gestureEvent.tapCount(),
-      static_cast<PlatformEvent::Modifiers>(
+      static_cast<WebInputEvent::Modifiers>(
           modifiers | WebInputEvent::Modifiers::LeftButtonDown |
           WebInputEvent::Modifiers::IsCompatibilityEventForTouch),
       gestureEvent.timeStampSeconds());
@@ -243,7 +243,7 @@ WebInputEventResult GestureManager::handleGestureTap(
   WebMouseEvent fakeMouseUp(
       WebInputEvent::MouseUp, gestureEvent, WebPointerProperties::Button::Left,
       gestureEvent.tapCount(),
-      static_cast<PlatformEvent::Modifiers>(
+      static_cast<WebInputEvent::Modifiers>(
           modifiers | WebInputEvent::Modifiers::IsCompatibilityEventForTouch),
       gestureEvent.timeStampSeconds());
   WebInputEventResult mouseUpEventResult =
@@ -365,7 +365,7 @@ WebInputEventResult GestureManager::sendContextMenuEventForGesture(
         WebInputEvent::MouseMove, gestureEvent,
         WebPointerProperties::Button::NoButton,
         /* clickCount */ 0,
-        static_cast<PlatformEvent::Modifiers>(
+        static_cast<WebInputEvent::Modifiers>(
             modifiers | WebInputEvent::IsCompatibilityEventForTouch),
         gestureEvent.timeStampSeconds());
     m_mouseEventManager->setMousePositionAndDispatchMouseEvent(
@@ -381,8 +381,8 @@ WebInputEventResult GestureManager::sendContextMenuEventForGesture(
   WebMouseEvent mouseEvent(
       eventType, gestureEvent, WebPointerProperties::Button::Right,
       /* clickCount */ 1,
-      static_cast<PlatformEvent::Modifiers>(
-          modifiers | PlatformEvent::Modifiers::RightButtonDown |
+      static_cast<WebInputEvent::Modifiers>(
+          modifiers | WebInputEvent::Modifiers::RightButtonDown |
           WebInputEvent::IsCompatibilityEventForTouch),
       gestureEvent.timeStampSeconds());