Make scroll offset type of float in cc

cc/base/math_util.cc

Index: cc/base/math_util.cc
diff --git a/cc/base/math_util.cc b/cc/base/math_util.cc
index 7ed0c9a8b712e75931bc3420aec581da2e5b66c2..5df1e5650d0428ba2ca87ff2c3870ac9ba6adce9 100644
--- a/cc/base/math_util.cc
+++ b/cc/base/math_util.cc
@@ -778,6 +778,12 @@ void MathUtil::AddToTracedValue(const gfx::Vector2dF& v,
   res->AppendDouble(v.y());
 }
 
+void MathUtil::AddToTracedValue(const gfx::ScrollOffset& v,
+                                base::debug::TracedValue* res) {
+  res->AppendDouble(v.x());
+  res->AppendDouble(v.y());
+}
+
 void MathUtil::AddToTracedValue(const gfx::QuadF& q,
                                 base::debug::TracedValue* res) {
   res->AppendDouble(q.p1().x());