Refactor SetClientID such that metrics rather than crash backs up the client id in Google Update set

chrome/app/client_util.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <windows.h>
 #include <shlwapi.h>
 
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/debug/trace_event.h"
@@ skipping 58 matching lines @@
   // Return true if the build time predates the expiration time..
   return build_time < expiration_time;
 }
 
 // Get random unit values, i.e., in the range (0, 1), denoting a die-toss for
 // being in an experiment population and experimental group thereof.
 void GetPreReadPopulationAndGroup(double* population, double* group) {
   // By default we use the metrics id for the user as stable pseudo-random
   // input to a hash.
   std::string metrics_id;
-  GoogleUpdateSettings::GetMetricsId(&metrics_id);
+  GoogleUpdateSettings::RetrieveMetricsID(&metrics_id);

[Ilya Sherman, 2014/07/08 03:21:38]

Optional nit: IMO "Get" and "Retrieve" are synonyms, but "Get" is shorter and
more commonly used.  Hence, I'd keep the previous name.

[gab, 2014/07/08 18:42:22]

Went with Load/Store as suggested by grt @
https://codereview.chromium.org/372473004/diff/80001/components/metrics/metri...

I find this makes it more explicit that it's external storage, not memory
storage.

 
   // If this user has not metrics id, we fall back to a purely random value
   // per browser session.
   const size_t kLength = 16;
   std::string random_value(metrics_id.empty() ? base::RandBytesAsString(kLength)
                                               : metrics_id);
 
   // To interpret the value as a random number we hash it and read the first 8
   // bytes of the hash as a unit-interval representing a die-toss for being in
   // the experiment population and the second 8 bytes as a die-toss for being
@@ skipping 272 matching lines @@
   }
 };
 
 MainDllLoader* MakeMainDllLoader() {
 #if defined(GOOGLE_CHROME_BUILD)
   return new ChromeDllLoader();
 #else
   return new ChromiumDllLoader();
 #endif
 }