Revert of Switch uses of SkChecksum::Compute to Murmur3.

src/core/SkPictureFlat.h

Index: src/core/SkPictureFlat.h
diff --git a/src/core/SkPictureFlat.h b/src/core/SkPictureFlat.h
index 8befca0538daf1f0f6f236cdab13cdcadf6b6a80..98a43ecb579454d22dc8042d97c0771a6c85509c 100644
--- a/src/core/SkPictureFlat.h
+++ b/src/core/SkPictureFlat.h
@@ -179,7 +179,7 @@
 
 class SkFlatController : public SkRefCnt {
 public:
-
+    
 
     SkFlatController(uint32_t writeBufferFlags = 0);
     virtual ~SkFlatController();
@@ -357,7 +357,7 @@
         fIndex     = index;
         fFlatSize  = size;
         fTopBot[0] = SK_ScalarNaN;  // Mark as unwritten.
-        fChecksum  = SkChecksum::Murmur3(this->data(), size);
+        fChecksum  = SkChecksum::Compute((uint32_t*)this->data(), size);
     }
 
     int fIndex;