Optimize CSS box-shadow performance by caching the SkMask of the blur effect.

src/effects/SkBlurMask.h

Index: src/effects/SkBlurMask.h
diff --git a/src/effects/SkBlurMask.h b/src/effects/SkBlurMask.h
index 71f60d91faabf5ab6642803f49660ca180119bd7..df695cf2e037c95259a76fd01e872330fb331dc3 100644
--- a/src/effects/SkBlurMask.h
+++ b/src/effects/SkBlurMask.h
@@ -7,6 +7,7 @@
 
 #ifndef SkBlurMask_DEFINED
 #define SkBlurMask_DEFINED
+#include <map>
 
 #include "SkBlurTypes.h"
 #include "SkShader.h"
@@ -75,8 +76,12 @@ public:
 
     static void ComputeBlurredScanline(uint8_t* pixels, const uint8_t* profile,
                                        unsigned int width, SkScalar sigma);
+    static bool addDiscardableMemoryMaskToMap(SkMask*, SkDiscardableMemoryMask*);
+    static bool removeDiscardableMemoryMaskFromMap(SkMask*);
+    static SkDiscardableMemoryMask* getDiscardableMemoryMaskFromMap(SkMask*);

[Stephen White, 2014/06/09 18:03:57]

Naming nit: similarly, could this be getCachedMask()? No need to expose that
it's a map or that it's backed by discardable memory, AFAICT.

 
-
+private:
+    static std::map<SkMask*, SkDiscardableMemoryMask*> fDiscardableMemoryMaskMap;
 
 };