cc: Do not create separate tilings for almost equal scale factors.

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 6e5ac0bd45db73b47d318a7d4b3aef0f42af0078..f4bc359059f9dfb57cc8aa103514048ca8d906e3 100644
--- a/cc/base/math_util.cc
+++ b/cc/base/math_util.cc
@@ -120,6 +120,18 @@ static inline void AddVertexToClippedQuad3d(const gfx::Point3F& new_vertex,
   (*num_vertices_in_clipped_quad)++;
 }
 
+float MathUtil::RoundToFixedPrecision(float value, int precision) {
+  // Return the same value, as higher precision is not possible with float.
+  if (precision < 1 || precision > (std::numeric_limits<float>::digits10 - 1))

[ericrk, 2015/10/19 16:40:50]

drive-by-nit: Should we DCHECK that precision >= 1? Or clamp to 1? returning the
full-precision number when a caller asks for precision 0 seems weird?

[vmpstr, 2015/10/19 18:58:38]

I agree, this should be a DCHECK instead of an early out.

+    return value;
+
+  float factor = std::pow(10, precision);
+  float integral;
+  float fractional = std::modf(value, &integral);
+  fractional = std::round(fractional * factor) / factor;
+  return integral + fractional;
+}
+
 gfx::Rect MathUtil::MapEnclosingClippedRect(const gfx::Transform& transform,
                                             const gfx::Rect& src_rect) {
   if (transform.IsIdentityOrIntegerTranslation()) {