Add DisplayPlacement/Layout mojoms + StructTraits.

ui/display/display_layout.h

 // 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.
 
 #ifndef UI_DISPLAY_DISPLAY_LAYOUT_H_
 #define UI_DISPLAY_DISPLAY_LAYOUT_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 51 matching lines @@
                    int offset,
                    OffsetReference offset_reference);
   DisplayPlacement(int64_t display_id,
                    int64_t parent_display_id,
                    Position position,
                    int offset,
                    OffsetReference offset_reference);
 
   DisplayPlacement(const DisplayPlacement& placement);
 
+  bool operator==(const DisplayPlacement& other) const;
+  bool operator!=(const DisplayPlacement& other) const;
+
   DisplayPlacement& Swap();
 
   std::string ToString() const;
 
   static std::string PositionToString(Position position);
   static bool StringToPosition(const base::StringPiece& string,
                                Position* position);
 };
 
 class DISPLAY_EXPORT DisplayLayout final {
@@ skipping 43 matching lines @@
   static bool ApplyDisplayPlacement(const DisplayPlacement& placement,
                                     Displays* display_list,
                                     int minimum_offset_overlap);
 
   DISALLOW_COPY_AND_ASSIGN(DisplayLayout);
 };
 
 }  // namespace display
 
 #endif  // UI_DISPLAY_DISPLAY_LAYOUT_H_