views: removes some dead code

BUG=none
TEST=none

Change-Id: Id233a340a9513fee590c76f35cf23a1395fbaf0c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2594427Reviewed-by: Allen Bauer <kylixrd@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#837719}

ui/views/win/hwnd_message_handler.cc

@@ -211,11 +211,6 @@ bool GetMonitorAndRects(const RECT& rect,
   return true;
 }
 
-struct FindOwnedWindowsData {
-  HWND window;
-  std::vector<Widget*> owned_widgets;
-};
-
 // Enables or disables the menu item for the specified command and menu.
 void EnableMenuItemByCommand(HMENU menu, UINT command, bool enabled) {
   UINT flags = MF_BYCOMMAND | (enabled ? MF_ENABLED : MF_DISABLED | MF_GRAYED);