Factoring GUID generation from metrics to base

base/rand_util_posix.cc

Index: base/rand_util_posix.cc
diff --git a/base/rand_util_posix.cc b/base/rand_util_posix.cc
index 43dfd1e7904914e71eea5eb235526ab42cecde48..6a0a203f6347176fae4282448cd95ab1c799fb98 100644
--- a/base/rand_util_posix.cc
+++ b/base/rand_util_posix.cc
@@ -12,6 +12,7 @@
 #include "base/file_util.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
+#include "base/stringprintf.h"
 
 namespace {
 
@@ -54,6 +55,22 @@ uint64 RandUint64() {
   return number;
 }
 
+// TODO(cmasone): Once we're comfortable this works, migrate Windows code to
+// use this as well.
+std::string RandomBytesToGUIDString(const uint64 bytes[2]) {
+  return StringPrintf("%08X-%04X-%04X-%04X-%012llX",
+                      static_cast<unsigned int>(bytes[0] >> 32),
+                      static_cast<unsigned int>((bytes[0] >> 16) & 0x0000ffff),
+                      static_cast<unsigned int>(bytes[0] & 0x0000ffff),
+                      static_cast<unsigned int>(bytes[1] >> 48),
+                      bytes[1] & 0x0000ffffffffffffULL);
+}
+
+std::string GenerateGUID() {
+  uint64 sixteen_bytes[2] = { base::RandUint64(), base::RandUint64() };
+  return RandomBytesToGUIDString(sixteen_bytes);
+}
+
 }  // namespace base
 
 int GetUrandomFD(void) {