Fix backspace double occuring on PDF files.

third_party/WebKit/public/platform/WebInputEvent.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 323 matching lines @@
         isSystemKey(false),
         isBrowserShortcut(false) {
     memset(&text, 0, sizeof(text));
     memset(&unmodifiedText, 0, sizeof(unmodifiedText));
   }
 
   // Please refer to bug http://b/issue?id=961192, which talks about Webkit
   // keyboard event handling changes. It also mentions the list of keys
   // which don't have associated character events.
   bool isCharacterKey() const {
-#if 0
+    // TODO(dtapuska): Determine if we can remove this method and just
+    // not actually generate events for these instead of filtering them out.
     switch (windowsKeyCode) {
-    case VKEY_BACK:
-    case VKEY_ESCAPE:
+      case 0x08:  // VK_BACK
+      case 0x1b:  // VK_ESCAPE
         return false;
     }
-#endif
     return true;
   }
 };
 
 // WebMouseEvent --------------------------------------------------------------
 
 class WebMouseEvent : public WebInputEvent, public WebPointerProperties {
  public:
   // Renderer coordinates. Similar to viewport coordinates but without
   // DevTools emulation transform or overscroll applied. i.e. the coordinates
@@ skipping 294 matching lines @@
         dispatchedDuringFling(false),
         touchStartOrFirstTouchMove(false),
         uniqueTouchEventId(0) {}
 };
 
 #pragma pack(pop)
 
 }  // namespace blink
 
 #endif