Make scroll offset type of float in cc

ui/gfx/geometry/scroll_offset.cc

+// Copyright 2014 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/scroll_offset.h"
+
+#include "base/strings/stringprintf.h"
+
+namespace gfx {
+
+std::string ScrollOffset::ToString() const {

[danakj, 2014/09/27 00:00:44]

nit: move to bottom like it is ordered in .cc

[Yufeng Shen (Slow to review), 2014/09/29 19:27:34]

with the 3 methods below moved into .cc, the order
is now correct :)

+  return base::StringPrintf("[%lf %lf]", x_, y_);
+}
+
+bool ScrollOffset::IsZero() const {

[danakj, 2014/09/27 00:00:44]

these 3 method are all trivial, can you move them to the header file?

[Yufeng Shen (Slow to review), 2014/09/29 19:27:34]

Done.

+  return x_ == 0 && y_ == 0;
+}
+
+void ScrollOffset::Add(const ScrollOffset& other) {
+  x_ += other.x_;
+  y_ += other.y_;
+}
+
+void ScrollOffset::Subtract(const ScrollOffset& other) {
+  x_ -= other.x_;
+  y_ -= other.y_;
+}
+
+}  // namespace gfx