Sort GL extension strings and search to find.

include/core/SkString.h

Index: include/core/SkString.h
===================================================================
--- include/core/SkString.h	(revision 7872)
+++ include/core/SkString.h	(working copy)
@@ -244,4 +244,10 @@
 /// Creates a new string and writes into it using a printf()-style format.
 SkString SkStringPrintf(const char* format, ...);
 
+// Specialized to take advantage of SkString's fast swap path. The unspecialized function is
+// declared in SkTypes.h and called by SkTSort.
+template <> inline void SkTSwap(SkString& a, SkString& b) {
+    a.swap(b);
+}
+
 #endif