gfx: Fix ToEnclosing/ToEnclosed math to deal with big numbers.

ui/gfx/geometry/rect.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 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 227 matching lines @@
       x : static_cast<int>(std::ceil(rect.right() * x_scale));
   int b = rect.height() == 0 ?
       y : static_cast<int>(std::ceil(rect.bottom() * y_scale));
   return Rect(x, y, r - x, b - y);
 }
 
 inline Rect ScaleToEnclosingRect(const Rect& rect, float scale) {
   return ScaleToEnclosingRect(rect, scale, scale);
 }
 
+// Returns the smallest Rect that encloses the given Rect after scaling by
+// scale. If the result is scaling would make any dimension of the rect be too

[danakj, 2015/06/15 19:13:47]

result from

+// big to be represented by an integer, then use the largest integer for that
+// dimension.
+// Note that the resulting rect x(), y(), width(), height(), right(), bottom()
+// will all return valid integer values. This means that if x() is max_int,
+// then width would() have to be 0 in order for right() to be max_int.
+GFX_EXPORT Rect SafelyScaleToEnclosingRect(const Rect& rect, float scale);

[danakj, 2015/06/15 19:13:47]

Should we be returning a bool equivalent of |clipped| in MathUtil stuff? Like
here's a rect but it's not actually enclosing. GLHF.

+
 inline Rect ScaleToEnclosedRect(const Rect& rect,
                                 float x_scale,
                                 float y_scale) {
   DCHECK(base::IsValueInRangeForNumericType<int>(
       std::ceil(rect.x() * x_scale)));
   DCHECK(base::IsValueInRangeForNumericType<int>(
       std::ceil(rect.y() * y_scale)));
   DCHECK(base::IsValueInRangeForNumericType<int>(
       std::floor(rect.right() * x_scale)));
   DCHECK(base::IsValueInRangeForNumericType<int>(
@@ skipping 12 matching lines @@
 }
 
 // This is declared here for use in gtest-based unit tests but is defined in
 // the gfx_test_support target. Depend on that to use this in your unit test.
 // This should not be used in production code - call ToString() instead.
 void PrintTo(const Rect& rect, ::std::ostream* os);
 
 }  // namespace gfx
 
 #endif  // UI_GFX_GEOMETRY_RECT_H_