Initial pass at integrating Differ into the chromoting host code....

gfx/point.h

 // Copyright (c) 2010 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 GFX_POINT_H_
 #define GFX_POINT_H_
 #pragma once
 
 #include "build/build_config.h"
 
@@ skipping 55 matching lines @@
   }
 
   bool operator==(const Point& rhs) const {
     return x_ == rhs.x_ && y_ == rhs.y_;
   }
 
   bool operator!=(const Point& rhs) const {
     return !(*this == rhs);
   }
 
+  // A point is less than another point if its y-value is closer
+  // to the origin. If the y-values are the same, then point with
+  // the x-value closer to the origin is considered less than the
+  // other.
+  // This comparison is required to use Points in sets, or sorted
+  // vectors.
+  bool operator<(const Point& rhs) const {
+    return (y_ == rhs.y_) ? (x_ < rhs.x_) : (y_ < rhs.y_);
+  }
+
 #if defined(OS_WIN)
   POINT ToPOINT() const;
 #elif defined(OS_MACOSX)
   CGPoint ToCGPoint() const;
 #endif
 
  private:
   int x_;
   int y_;
 };
 
 }  // namespace gfx
 
 std::ostream& operator<<(std::ostream& out, const gfx::Point& p);
 
 #endif  // GFX_POINT_H_