Attempt at fixing color cube bench

The original bench was hitting the cache since it was using the same color filter for all loops. By creating a new color filter within the loop, at least this part of it is solved. I'm not 100% sure this is the right way, but at least the numbers are a bit more reasonable and are affected by the output resolution.

BUG=skia:

Review URL: https://codereview.chromium.org/648483002

bench/ColorCubeBench.cpp

@@ -94,12 +94,11 @@ private:
     }
 
     void test(const int loops, SkCanvas* canvas) {
-        SkAutoTUnref<SkColorFilter> colorCube(
-            SkColorCubeFilter::Create(fCubeData, fCubeDimension));
         SkPaint paint;
-        paint.setColorFilter(colorCube);
-
         for (int i = 0; i < loops; i++) {
+            SkAutoTUnref<SkColorFilter> colorCube(
+                SkColorCubeFilter::Create(fCubeData, fCubeDimension));
+            paint.setColorFilter(colorCube);
             canvas->drawBitmap(fBitmap, 0, 0, &paint);
         }
     }