Inline gfx::Vector2d* ctors and integer conversions

ui/gfx/vector2d_f.h

 // Copyright (c) 2012 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 float vector class.  This class is used to indicate a
 // distance in two dimensions between two points. Subtracting two points should
 // produce a vector, and adding a vector to a point produces the point at the
 // vector's distance from the original point.
 
 #ifndef UI_GFX_VECTOR2D_F_H_
 #define UI_GFX_VECTOR2D_F_H_
 
 #include <string>
 
 #include "ui/base/ui_export.h"
 
 namespace gfx {
 
 class UI_EXPORT Vector2dF {
  public:
-  Vector2dF();
-  Vector2dF(float x, float y);
+  Vector2dF() : x_(0), y_(0) {}
+  Vector2dF(float x, float y) : x_(x), y_(y) {}
 
   float x() const { return x_; }
   void set_x(float x) { x_ = x; }
 
   float y() const { return y_; }
   void set_y(float y) { y_ = y; }
 
   // True if both components of the vector are 0.
   bool IsZero() const;
 
@@ skipping 66 matching lines @@
                                   float y_scale);
 
 // Return a vector that is |v| scaled by the given scale factor.
 inline Vector2dF ScaleVector2d(const Vector2dF& v, float scale) {
   return ScaleVector2d(v, scale, scale);
 }
 
 }  // namespace gfx
 
 #endif // UI_GFX_VECTOR2D_F_H_