Optimize CSS box-shadow performance

src/effects/SkBlurMaskFilter.cpp

Index: src/effects/SkBlurMaskFilter.cpp
diff --git a/src/effects/SkBlurMaskFilter.cpp b/src/effects/SkBlurMaskFilter.cpp
index e4133a8bceff3ec689c253afb671de8a3113c5fe..59ccdfd14219169257b4e7e8c2a149a071b5ff89 100644
--- a/src/effects/SkBlurMaskFilter.cpp
+++ b/src/effects/SkBlurMaskFilter.cpp
@@ -11,6 +11,7 @@
 #include "SkGpuBlurUtils.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
+#include "SkMaskCache.h"
 #include "SkMaskFilter.h"
 #include "SkRRect.h"
 #include "SkRTConf.h"
@@ -368,6 +369,14 @@ SkBlurMaskFilterImpl::filterRRectToNine(const SkRRect& rrect, const SkMatrix& ma
     radii[SkRRect::kLowerLeft_Corner] = LL;
     smallRR.setRectRadii(smallR, radii);
 
+    SkScalar sigma = this->computeXformedSigma(matrix);
+    if (SkMaskCache::Find(sigma, rrect, &patch->fMask)) {
+        patch->fOuterRect = dstM.fBounds;
+        patch->fCenter.fX = SkScalarCeilToInt(leftUnstretched) + 1;
+        patch->fCenter.fY = SkScalarCeilToInt(topUnstretched) + 1;
+        return kTrue_FilterReturn;
+    }
+
     bool analyticBlurWorked = false;
     if (c_analyticBlurRRect) {
         analyticBlurWorked =
@@ -391,6 +400,8 @@ SkBlurMaskFilterImpl::filterRRectToNine(const SkRRect& rrect, const SkMatrix& ma
     patch->fOuterRect = dstM.fBounds;
     patch->fCenter.fX = SkScalarCeilToInt(leftUnstretched) + 1;
     patch->fCenter.fY = SkScalarCeilToInt(topUnstretched) + 1;
+    SkMaskCache::Add(sigma, rrect, patch->fMask);
+
     return kTrue_FilterReturn;
 }
 
@@ -470,6 +481,13 @@ SkBlurMaskFilterImpl::filterRectsToNine(const SkRect rects[], int count,
                    smallH + (innerIR.top() - srcM.fBounds.top()));
     }
 
+    SkScalar sigma = this->computeXformedSigma(matrix);
+    if (SkMaskCache::Find(sigma, count, rects, &patch->fMask)) {
+        patch->fOuterRect = dstM.fBounds;
+        patch->fCenter = center;
+        return kTrue_FilterReturn;
+    }
+
     // +1 so we get a clean, stretchable, center row/col
     smallW += 1;
     smallH += 1;
@@ -513,6 +531,8 @@ SkBlurMaskFilterImpl::filterRectsToNine(const SkRect rects[], int count,
     patch->fMask.fBounds.offsetTo(0, 0);
     patch->fOuterRect = dstM.fBounds;
     patch->fCenter = center;
+    SkMaskCache::Add(sigma, count, rects, patch->fMask);
+
     return kTrue_FilterReturn;
 }
 
@@ -917,7 +937,6 @@ GrEffect* GrRRectBlurEffect::Create(GrContext* context, float sigma, const SkRRe
         SkBlurMask::BoxBlur(&blurred_mask, mask, sigma, kNormal_SkBlurStyle, kHigh_SkBlurQuality, NULL, true );
 
         blurNinePatchTexture = context->createTexture(&params, texDesc, blurRRectNinePatchID, blurred_mask.fImage, 0);
-        SkMask::FreeImage(blurred_mask.fImage);
     }
 
     SkAutoTUnref<GrTexture> blurunref(blurNinePatchTexture);