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

gfx/rect.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.
 
 // Defines a simple integer rectangle class.  The containment semantics
 // are array-like; that is, the coordinate (x, y) is considered to be
 // contained by the rectangle, but the coordinate (x + width, y) is not.
 // The class will happily let you create malformed rectangles (that is,
 // rectangles with negative width and/or height), but there will be assertions
 // in the operations (such as Contains()) to complain in this case.
@@ skipping 84 matching lines @@
 
   // Returns true if the area of the rectangle is zero.
   bool IsEmpty() const { return size_.IsEmpty(); }
 
   bool operator==(const Rect& other) const;
 
   bool operator!=(const Rect& other) const {
     return !(*this == other);
   }
 
+  // A rect is less than another rect if its origin is less than
+  // the other rect's origin. If the origins are equal, then the
+  // shortest rect is less than the other. If the origin and the
+  // height are equal, then the narrowest rect is less than.
+  // This comparison is required to use Rects in sets, or sorted
+  // vectors.
+  bool operator<(const Rect& other) const;
+
 #if defined(OS_WIN)
   // Construct an equivalent Win32 RECT object.
   RECT ToRECT() const;
 #elif defined(USE_X11)
   GdkRectangle ToGdkRectangle() const;
 #elif defined(OS_MACOSX)
   // Construct an equivalent CoreGraphics object.
   CGRect ToCGRect() const;
 #endif
 
@@ skipping 48 matching lines @@
  private:
   gfx::Point origin_;
   gfx::Size size_;
 };
 
 }  // namespace gfx
 
 std::ostream& operator<<(std::ostream& out, const gfx::Rect& r);
 
 #endif  // GFX_RECT_H_