Optimize CSS box-shadow performance

src/core/SkMaskCache.cpp

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkMaskCache.h"
+#include "SkBitmapCache.h"
+
+bool SkMaskCache::Find(SkScalar sigma, const SkRRect& rrect, SkMask* result) {
+    if (SkBitmapCache::Find(sigma, rrect, &result->fBitmap)) {
+        result->fBounds.set(0, 0, result->fBitmap.width(), result->fBitmap.height());
+        result->fRowBytes = result->fBounds.width();
+        result->fFormat = SkMask::kA8_Format;
+        result->fImage = result->fBitmap.getAddr8(0, 0);
+        return true;
+    }
+    return false;
+}
+
+void SkMaskCache::Add(SkScalar sigma, const SkRRect& rrect, const SkMask& mask) {
+    SkBitmapCache::Add(sigma, rrect, mask.fBitmap);
+}
+
+//////////////////////////////////////////////////////////////////////////////////////////
+
+bool SkMaskCache::Find(SkScalar sigma, int32_t count, const SkRect rects[], SkMask* result) {
+    if (SkBitmapCache::Find(sigma, count, rects, &result->fBitmap)) {
+        result->fBounds.set(0, 0, result->fBitmap.width(), result->fBitmap.height());
+        result->fRowBytes = result->fBounds.width();
+        result->fFormat = SkMask::kA8_Format;
+        result->fImage = result->fBitmap.getAddr8(0, 0);
+        return true;
+    }
+    return false;
+}
+
+void SkMaskCache::Add(SkScalar sigma, int32_t count, const SkRect rects[], const SkMask& mask) {
+    SkBitmapCache::Add(sigma, count, rects, mask.fBitmap);
+}
+