Make scroll offset type of float in cc

ui/gfx/geometry/safe_integer_conversions.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.
 
 #ifndef UI_GFX_GEOMETRY_SAFE_INTEGER_CONVERSIONS_H_
 #define UI_GFX_GEOMETRY_SAFE_INTEGER_CONVERSIONS_H_
 
 #include <cmath>
 #include <limits>
 
@@ skipping 12 matching lines @@
 }
 
 inline int ToFlooredInt(float value) {
   return ClampToInt(std::floor(value));
 }
 
 inline int ToCeiledInt(float value) {
   return ClampToInt(std::ceil(value));
 }
 
+inline int ToFlooredInt(double value) {
+  return ClampToInt(std::floor(value));
+}
+
+inline int ToCeiledInt(double value) {
+  return ClampToInt(std::ceil(value));
+}
+
 inline int ToRoundedInt(float value) {
   float rounded;
   if (value >= 0.0f)
     rounded = std::floor(value + 0.5f);
   else
     rounded = std::ceil(value - 0.5f);
   return ClampToInt(rounded);
 }
 
 inline bool IsExpressibleAsInt(float value) {
   if (value != value)
     return false; // no int NaN.
   if (value > std::numeric_limits<int>::max())
     return false;
   if (value < std::numeric_limits<int>::min())
     return false;
   return true;
 }
 
 }  // namespace gfx
 
 #endif  // UI_GFX_GEOMETRY_SAFE_INTEGER_CONVERSIONS_H_