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

3 files changed, 49 insertions, 38 deletions

diff --git a/gyp/core.gypi b/gyp/core.gypi
index c71ea317c7..85bc351372 100644
--- a/gyp/core.gypi
+++ b/gyp/core.gypi
@@ -65,6 +65,7 @@
         '<(skia_src_path)/core/SkCachedData.cpp',
         '<(skia_src_path)/core/SkCanvas.cpp',
         '<(skia_src_path)/core/SkCanvasPriv.h',
+        '<(skia_src_path)/core/SkChecksum.cpp',
         '<(skia_src_path)/core/SkChunkAlloc.cpp',
         '<(skia_src_path)/core/SkClipStack.cpp',
         '<(skia_src_path)/core/SkColor.cpp',
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
diff --git a/src/core/SkChecksum.cpp b/src/core/SkChecksum.cpp
new file mode 100644
index 0000000000..4457eb4f99
--- /dev/null
+++ b/src/core/SkChecksum.cpp
@@ -0,0 +1,47 @@
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkChecksum.h"
+
+uint32_t SkChecksum::Murmur3(const void* data, size_t bytes, uint32_t seed) {
+    // 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 SkChecksum::Mix(hash);
+}