Re-land "Move CachingPermutedEntropyProvider to its own file."

Reland of https://codereview.chromium.org/21127007/

The original CL changed a std::string to a const char* in
a test, which resulted in saving a ref to a temporary that
was later deref'd, which is now fixed in this CL.

BUG=266007
TEST=Existing unit tests.
[email protected],[email protected]
NOTRY=true

Review URL: https://chromiumcodereview.appspot.com/21893002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@215291 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/chrome/browser/metrics/metrics_service.cc b/chrome/browser/metrics/metrics_service.cc
index d48eb7b..3e8d17a 100644
--- a/chrome/browser/metrics/metrics_service.cc
+++ b/chrome/browser/metrics/metrics_service.cc
@@ -194,6 +194,7 @@
 #include "chrome/common/child_process_logging.h"
 #include "chrome/common/chrome_result_codes.h"
 #include "chrome/common/chrome_switches.h"
+#include "chrome/common/metrics/caching_permuted_entropy_provider.h"
 #include "chrome/common/metrics/entropy_provider.h"
 #include "chrome/common/metrics/metrics_log_manager.h"
 #include "chrome/common/net/test_server_locations.h"