Move SkChecksum::Murmur3 out of the header.

As we use this more and more, we end up with more and more inline copies.
On my desktop, this makes Skia ~16K smaller.

Boy perf trybots would be neat.

BUG=skia:

Review URL: https://codereview.chromium.org/1415133003

1 files changed, 1 insertions, 38 deletions

diff --git a/include/private/SkChecksum.h b/include/private/SkChecksum.h
index cbc8a73a3e..4526416fc1 100644
--- a/include/private/SkChecksum.h
+++ b/include/private/SkChecksum.h
@@ -76,44 +76,7 @@ public:
      *  @param seed Initial hash seed. (optional)
      *  @return hash result
      */
-    static uint32_t Murmur3(const void* data, size_t bytes, uint32_t seed=0) {
-        // Use may_alias to remind the compiler we're intentionally violating strict aliasing,
-        // and so not to apply strict-aliasing-based optimizations.
-        typedef uint32_t SK_ATTRIBUTE(may_alias) aliased_uint32_t;
-        typedef uint8_t SK_ATTRIBUTE(may_alias) aliased_uint8_t;
-
-        // Handle 4 bytes at a time while possible.
-        const aliased_uint32_t* safe_data = (const aliased_uint32_t*)data;
-        const size_t words = bytes/4;
-        uint32_t hash = seed;
-        for (size_t i = 0; i < words; i++) {
-            uint32_t k = safe_data[i];
-            k *= 0xcc9e2d51;
-            k = (k << 15) | (k >> 17);
-            k *= 0x1b873593;
-
-            hash ^= k;
-            hash = (hash << 13) | (hash >> 19);
-            hash *= 5;
-            hash += 0xe6546b64;
-        }
-
-        // Handle last 0-3 bytes.
-        const aliased_uint8_t* safe_tail = (const uint8_t*)(safe_data + words);
-        uint32_t k = 0;
-        switch (bytes & 3) {
-            case 3: k ^= safe_tail[2] << 16;
-            case 2: k ^= safe_tail[1] <<  8;
-            case 1: k ^= safe_tail[0] <<  0;
-                    k *= 0xcc9e2d51;
-                    k = (k << 15) | (k >> 17);
-                    k *= 0x1b873593;
-                    hash ^= k;
-        }
-
-        hash ^= bytes;
-        return Mix(hash);
-    }
+    static uint32_t Murmur3(const void* data, size_t bytes, uint32_t seed=0);
 
     /**
      *  Compute a 32-bit checksum for a given data block