Revert of Slim Skia down to just one murmur3 implementation.

src/core/SkChecksum.h

Index: src/core/SkChecksum.h
diff --git a/src/core/SkChecksum.h b/src/core/SkChecksum.h
index fe1e9584a20e8e87c2475a648af21e03db9e6710..bf3228f91db8722337e9b06db0fb23fb491d4e37 100644
--- a/src/core/SkChecksum.h
+++ b/src/core/SkChecksum.h
@@ -36,20 +36,6 @@
     }
 
 public:
-    /**
-     * uint32_t -> uint32_t hash, useful for when you're about to trucate this hash but you
-     * suspect its low bits aren't well mixed.
-     *
-     * This is the Murmur3 finalizer.
-     */
-    static uint32_t Mix(uint32_t hash) {
-        hash ^= hash >> 16;
-        hash *= 0x85ebca6b;
-        hash ^= hash >> 13;
-        hash *= 0xc2b2ae35;
-        hash ^= hash >> 16;
-        return hash;
-    }
 
     /**
      * Calculate 32-bit Murmur hash (murmur3).
@@ -62,7 +48,7 @@
      *  @return hash result
      */
     static uint32_t Murmur3(const uint32_t* data, size_t bytes, uint32_t seed=0) {
-        SkASSERTF(SkIsAlign4(bytes), "Expected 4-byte multiple, got %zu", bytes);
+        SkASSERT(SkIsAlign4(bytes));
         const size_t words = bytes/4;
 
         uint32_t hash = seed;
@@ -78,7 +64,12 @@
             hash += 0xe6546b64;
         }
         hash ^= bytes;
-        return Mix(hash);
+        hash ^= hash >> 16;
+        hash *= 0x85ebca6b;
+        hash ^= hash >> 13;
+        hash *= 0xc2b2ae35;
+        hash ^= hash >> 16;
+        return hash;
     }
 
     /**