Cleanup: Match the declaration order of MD5Sum() with the definition.

This puts the declaration of MD5Sum() function in sync with the
definition, which is right after MD5DigestToBase16() in the source file,
so it should be in the header file as well.

BUG=None
TEST=base_unittests --gtest_filter=MD5*
R=thestig@chromium.org

Review URL: https://codereview.chromium.org/1061903004

Cr-Commit-Position: refs/heads/master@{#324058}

base/md5.h

@@ -44,10 +44,6 @@ struct MD5Digest {
 // should not access the data.
 typedef char MD5Context[88];
 
-// Computes the MD5 sum of the given data buffer with the given length.
-// The given 'digest' structure will be filled with the result data.
-BASE_EXPORT void MD5Sum(const void* data, size_t length, MD5Digest* digest);
-
 // Initializes the given MD5 context structure for subsequent calls to
 // MD5Update().
 BASE_EXPORT void MD5Init(MD5Context* context);
@@ -69,6 +65,10 @@ BASE_EXPORT void MD5IntermediateFinal(MD5Digest* digest,
 // Converts a digest into human-readable hexadecimal.
 BASE_EXPORT std::string MD5DigestToBase16(const MD5Digest& digest);
 
+// Computes the MD5 sum of the given data buffer with the given length.
+// The given 'digest' structure will be filled with the result data.
+BASE_EXPORT void MD5Sum(const void* data, size_t length, MD5Digest* digest);
+
 // Returns the MD5 (in hexadecimal) of a string.
 BASE_EXPORT std::string MD5String(const StringPiece& str);