Provide a function to print the name of a Format.

include/images/SkImageDecoder.h

Index: include/images/SkImageDecoder.h
diff --git a/include/images/SkImageDecoder.h b/include/images/SkImageDecoder.h
index f6f64e15b3f4a7b657b61e342d0da341f95c2542..ba22652f18392a3315ad0bad002b33b75b43b5a3 100644
--- a/include/images/SkImageDecoder.h
+++ b/include/images/SkImageDecoder.h
@@ -49,6 +49,10 @@ public:
     */
     static Format GetStreamFormat(SkStream*);
 
+    /** Return a readable string of the Format provided.
+    */
+    static const char* GetFormatName(Format);
+
     /** Return a readable string of the value returned by getFormat().
     */
     const char* getFormatName() const;