Remove PlatformEvent it is no longer used.

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "KeyboardEventManager.h"
 
 #include "core/dom/DocumentUserGestureToken.h"
 #include "core/dom/Element.h"
 #include "core/editing/Editor.h"
 #include "core/events/KeyboardEvent.h"
@@ skipping 40 matching lines @@
   else if (event->key() == "ArrowUp")
     retVal = WebFocusTypeUp;
   else if (event->key() == "ArrowLeft")
     retVal = WebFocusTypeLeft;
   else if (event->key() == "ArrowRight")
     retVal = WebFocusTypeRight;
   return retVal;
 }
 
 bool mapKeyCodeForScroll(int keyCode,
-                         PlatformEvent::Modifiers modifiers,
+                         WebInputEvent::Modifiers modifiers,
                          ScrollDirection* scrollDirection,
                          ScrollGranularity* scrollGranularity) {
-  if (modifiers & PlatformEvent::ShiftKey || modifiers & PlatformEvent::MetaKey)
+  if (modifiers & WebInputEvent::ShiftKey || modifiers & WebInputEvent::MetaKey)
     return false;
 
-  if (modifiers & PlatformEvent::AltKey) {
+  if (modifiers & WebInputEvent::AltKey) {
     // Alt-Up/Down should behave like PageUp/Down on Mac.  (Note that Alt-keys
     // on other platforms are suppressed due to isSystemKey being set.)
     if (keyCode == VKEY_UP)
       keyCode = VKEY_PRIOR;
     else if (keyCode == VKEY_DOWN)
       keyCode = VKEY_NEXT;
     else
       return false;
   }
 
-  if (modifiers & PlatformEvent::CtrlKey) {
+  if (modifiers & WebInputEvent::ControlKey) {
     // Match FF behavior in the sense that Ctrl+home/end are the only Ctrl
     // key combinations which affect scrolling.
     if (keyCode != VKEY_HOME && keyCode != VKEY_END)
       return false;
   }
 
   switch (keyCode) {
     case VKEY_LEFT:
       *scrollDirection = ScrollLeftIgnoringWritingMode;
       *scrollGranularity = ScrollByLine;
@@ skipping 366 matching lines @@
   if (currentModifiers & ::cmdKey)
     modifiers |= WebInputEvent::MetaKey;
 #else
   // TODO(crbug.com/538289): Implement on other platforms.
   return static_cast<WebInputEvent::Modifiers>(0);
 #endif
   return static_cast<WebInputEvent::Modifiers>(modifiers);
 }
 
 }  // namespace blink