SSE2 implementation of RGBA box blurs. This yields ~2X perf improvement on

src/opts/SkBlurImage_opts.h

Index: src/opts/SkBlurImage_opts.h
diff --git a/src/opts/SkBlurImage_opts.h b/src/opts/SkBlurImage_opts.h
new file mode 100644
index 0000000000000000000000000000000000000000..07ac044fb15eb149321a97d049c703822bdb0a1a
--- /dev/null
+++ b/src/opts/SkBlurImage_opts.h
@@ -0,0 +1,21 @@
+/*
+ * Copyright 2013 The Android Open Source Project
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkBlurImage_opts_DEFINED
+#define SkBlurImage_opts_DEFINED
+
+#include "SkColorPriv.h"
+
+typedef void (*SkBoxBlurProc)(const SkPMColor* src, int srcStride, SkPMColor* dst, int kernelSize,
+                              int leftOffset, int rightOffset, int width, int height);
+
+enum SkBlurDirection {
+    kX_BlurDirection, kY_BlurDirection
+};
+
+SkBoxBlurProc SkBoxBlurGetPlatformProc(SkBlurDirection srcDirection, SkBlurDirection dstDirection);
+#endif