Implementation of principal-component color reduction.

ui/gfx/vector3d_f.h

Index: ui/gfx/vector3d_f.h
diff --git a/ui/gfx/vector3d_f.h b/ui/gfx/vector3d_f.h
index bb93abdeaffb8d1e325123e65df121c27b1ea31f..bf48298ce78603d6102081ab946cc83ab0165807 100644
--- a/ui/gfx/vector3d_f.h
+++ b/ui/gfx/vector3d_f.h
@@ -104,8 +104,14 @@ inline Vector3dF CrossProduct(const Vector3dF& lhs, const Vector3dF& rhs) {
   return result;
 }
 
+// Return the dot product of two vectors with the second given as xyz.
+UI_EXPORT float DotProduct(const Vector3dF& lhs, float x, float y, float z);
+
 // Return the dot product of two vectors.
-UI_EXPORT float DotProduct(const Vector3dF& lhs, const Vector3dF& rhs);
+inline float DotProduct(const Vector3dF& lhs, const Vector3dF& rhs) {
+  return DotProduct(lhs, rhs.x(), rhs.y(), rhs.z());
+}
+
 
 // Return a vector that is |v| scaled by the given scale factors along each
 // axis.