Do not convert from RectF to Rect by flooring.

ui/gfx/rect_conversions.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/rect_conversions.h"
+
+#include "ui/gfx/safe_floor_ceil.h"
+
+namespace gfx {
+
+Rect ToEnclosingRect(const RectF& rect) {
+  int min_x = ToFlooredInt(rect.origin().x());
+  int min_y = ToFlooredInt(rect.origin().y());
+  float max_x = rect.origin().x() + rect.size().width();
+  float max_y = rect.origin().y() + rect.size().height();
+  int width = std::max(ToCeiledInt(max_x) - min_x, 0);
+  int height = std::max(ToCeiledInt(max_y) - min_y, 0);
+  return Rect(min_x, min_y, width, height);
+}
+
+Rect ToEnclosedRect(const RectF& rect) {
+  int min_x = ToCeiledInt(rect.origin().x());
+  int min_y = ToCeiledInt(rect.origin().y());
+  float max_x = rect.origin().x() + rect.size().width();
+  float max_y = rect.origin().y() + rect.size().height();
+  int width = std::max(ToFlooredInt(max_x) - min_x, 0);
+  int height = std::max(ToFlooredInt(max_y) - min_y, 0);
+  return Rect(min_x, min_y, width, height);
+}
+
+}  // namespace gfx
+