Revert of Slim Skia down to just one murmur3 implementation.

src/core/SkScaledImageCache.cpp

Index: src/core/SkScaledImageCache.cpp
diff --git a/src/core/SkScaledImageCache.cpp b/src/core/SkScaledImageCache.cpp
index 1e7f51dd9e851d94a6c387e258f3512637c85e3f..eda4871711157cc2d64478867b774868fe7fb58d 100644
--- a/src/core/SkScaledImageCache.cpp
+++ b/src/core/SkScaledImageCache.cpp
@@ -5,7 +5,6 @@
  * found in the LICENSE file.
  */
 
-#include "SkChecksum.h"
 #include "SkScaledImageCache.h"
 #include "SkMipMap.h"
 #include "SkPixelRef.h"
@@ -28,6 +27,32 @@
 
 static inline SkScaledImageCache::Rec* id_to_rec(SkScaledImageCache::ID* id) {
     return reinterpret_cast<SkScaledImageCache::Rec*>(id);
+}
+
+ // Implemented from en.wikipedia.org/wiki/MurmurHash.
+static uint32_t compute_hash(const uint32_t data[], int count) {
+    uint32_t hash = 0;
+
+    for (int i = 0; i < count; ++i) {
+        uint32_t k = data[i];
+        k *= 0xcc9e2d51;
+        k = (k << 15) | (k >> 17);
+        k *= 0x1b873593;
+
+        hash ^= k;
+        hash = (hash << 13) | (hash >> 19);
+        hash *= 5;
+        hash += 0xe6546b64;
+    }
+
+    //    hash ^= size;
+    hash ^= hash >> 16;
+    hash *= 0x85ebca6b;
+    hash ^= hash >> 13;
+    hash *= 0xc2b2ae35;
+    hash ^= hash >> 16;
+
+    return hash;
 }
 
 struct SkScaledImageCache::Key {
@@ -39,7 +64,7 @@
         , fScaleX(scaleX)
         , fScaleY(scaleY)
         , fBounds(bounds) {
-        fHash = SkChecksum::Murmur3(&fGenID, 28);
+        fHash = compute_hash(&fGenID, 7);
     }
 
     bool operator<(const Key& other) const {