simplify bitmap scaler and cache

BUG=skia:

Review URL: https://codereview.chromium.org/1320513005
diff --git a/tests/SkResourceCacheTest.cpp b/tests/SkResourceCacheTest.cpp
index 6314863..cf8327f 100644
--- a/tests/SkResourceCacheTest.cpp
+++ b/tests/SkResourceCacheTest.cpp
@@ -21,9 +21,9 @@
                                      SkScalar xScale,
                                      SkScalar yScale) {
     SkBitmap scaled;
-    float roundedImageWidth = SkScalarRoundToScalar(orig.width() * xScale);
-    float roundedImageHeight = SkScalarRoundToScalar(orig.height() * yScale);
-    return SkBitmapCache::Find(orig, roundedImageWidth, roundedImageHeight, &scaled);
+    int width = SkScalarRoundToInt(orig.width() * xScale);
+    int height = SkScalarRoundToInt(orig.height() * yScale);
+    return SkBitmapCache::FindWH(orig, width, height, &scaled);
 }
 
 // Draw a scaled bitmap, then return true if it has been cached.