Fix overflow/underflow in gfx geometry once and for all

ui/gfx/geometry/size.cc

 // 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.
 
 #include "ui/gfx/geometry/size.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #elif defined(OS_IOS)
 #include <CoreGraphics/CoreGraphics.h>
 #elif defined(OS_MACOSX)
 #include <ApplicationServices/ApplicationServices.h>
 #endif
 
 #include "base/numerics/safe_math.h"
 #include "base/strings/stringprintf.h"
 #include "build/build_config.h"
+#include "ui/gfx/geometry/safe_integer_conversions.h"
 #include "ui/gfx/geometry/size_conversions.h"
 
 namespace gfx {
 
 #if defined(OS_MACOSX)
 Size::Size(const CGSize& s)
     : width_(s.width < 0 ? 0 : s.width),
       height_(s.height < 0 ? 0 : s.height) {
 }
 
@@ skipping 21 matching lines @@
   return GetCheckedArea().ValueOrDie();
 }
 
 base::CheckedNumeric<int> Size::GetCheckedArea() const {
   base::CheckedNumeric<int> checked_area = width();
   checked_area *= height();
   return checked_area;
 }
 
 void Size::Enlarge(int grow_width, int grow_height) {
-  SetSize(width() + grow_width, height() + grow_height);
+  SetSize(SafeAdd(width(), grow_width), SafeAdd(height(), grow_height));
 }
 
 void Size::SetToMin(const Size& other) {
   width_ = width() <= other.width() ? width() : other.width();
   height_ = height() <= other.height() ? height() : other.height();
 }
 
 void Size::SetToMax(const Size& other) {
   width_ = width() >= other.width() ? width() : other.width();
   height_ = height() >= other.height() ? height() : other.height();
@@ skipping 33 matching lines @@
   return ToRoundedSize(ScaleSize(gfx::SizeF(size), x_scale, y_scale));
 }
 
 Size ScaleToRoundedSize(const Size& size, float scale) {
   if (scale == 1.f)
     return size;
   return ToRoundedSize(ScaleSize(gfx::SizeF(size), scale, scale));
 }
 
 }  // namespace gfx