PageOverlays: Remove PageOverlayList

Source/web/web.gypi

 {
   'variables': {
     'web_files': [
       'AssertMatchingEnums.cpp',
       'AssociatedURLLoader.cpp',
       'AssociatedURLLoader.h',
       'ChromeClientImpl.cpp',
       'ChromeClientImpl.h',
       'ColorChooserPopupUIController.cpp',
       'ColorChooserPopupUIController.h',
@@ skipping 47 matching lines @@
       'MediaKeysClientImpl.cpp',
       'MediaKeysClientImpl.h',
       'NavigatorContentUtilsClientImpl.cpp',
       'NavigatorContentUtilsClientImpl.h',
       'NotificationPermissionClientImpl.cpp',
       'NotificationPermissionClientImpl.h',
       'OpenedFrameTracker.cpp',
       'OpenedFrameTracker.h',
       'PageOverlay.cpp',
       'PageOverlay.h',
-      'PageOverlayList.cpp',
-      'PageOverlayList.h',
       'PageWidgetDelegate.cpp',
       'PageWidgetDelegate.h',
       'PluginPlaceholderImpl.cpp',
       'PluginPlaceholderImpl.h',
       'PopupMenuImpl.cpp',
       'PopupMenuImpl.h',
       'PrerendererClientImpl.cpp',
       'PrerendererClientImpl.h',
       'RemoteBridgeFrameOwner.cpp',
       'RemoteBridgeFrameOwner.h',
@@ skipping 232 matching lines @@
         {
           'web_unittest_files': [
             # Mac uses ScrollAnimatorMac instead of ScrollAnimatorNone.
             'tests/ScrollAnimatorNoneTest.cpp',
           ],
         }
       ],
     ],
   },
 }