PM: Various fixes to Random Provider

* Remove mention of uint64; use uint64_t instead.

* Simpler reading of bytes from /dev/urandom into a uint64_t.

* Replace string concatenation with StringPrintf.

BUG=None
TEST=Builds and passes unit tests.

Change-Id: Ic0760ae4c2b21e4ffc823a676a9439e867bf9f64
Reviewed-on: https://chromium-review.googlesource.com/184326
Reviewed-by: Gilad Arnold <garnold@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
Tested-by: Gilad Arnold <garnold@chromium.org>
diff --git a/policy_manager/random_provider_unittest.cc b/policy_manager/random_provider_unittest.cc
index af11b6e..265050e 100644
--- a/policy_manager/random_provider_unittest.cc
+++ b/policy_manager/random_provider_unittest.cc
@@ -40,7 +40,7 @@
 
 TEST_F(PmRandomProviderTest, GetRandomValues) {
   string errmsg;
-  scoped_ptr<const uint64> value(
+  scoped_ptr<const uint64_t> value(
       var_random_seed->GetValue(TimeDelta::FromSeconds(1.), &errmsg));
   ASSERT_TRUE(value != NULL);
 
@@ -48,7 +48,7 @@
   // Test that at least the returned values are different. This test fails,
   // by design, once every 2^320 runs.
   for (int i = 0; i < 5; i++) {
-    scoped_ptr<const uint64> other_value(
+    scoped_ptr<const uint64_t> other_value(
         var_random_seed->GetValue(TimeDelta::FromSeconds(1.), &errmsg));
     ASSERT_TRUE(other_value != NULL);
     always_returns_the_same_value = always_returns_the_same_value &&