Clear client id prefs when opting out of UMA.

chrome/browser/android/metrics/uma_session_stats.cc

 // Copyright 2015 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 "chrome/browser/android/metrics/uma_session_stats.h"
 
 #include "base/android/jni_array.h"
 #include "base/android/jni_string.h"
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
@@ skipping 99 matching lines @@
   if (metrics->recording_active() != may_record) {
     // This function puts a consent file with the ClientID in the
     // data directory. The ID is passed to the renderer for crash
     // reporting when things go wrong.
     content::BrowserThread::GetBlockingPool()->PostTask(FROM_HERE,
         base::Bind(
             base::IgnoreResult(GoogleUpdateSettings::SetCollectStatsConsent),
             may_record));
   }
 
+  // Clear the client id pref when opting out. Note: Mirrors code in
+  // metrics_reporting_state.cc. TODO(asvitkine): Unify.
+  if (!may_record) {
+    // Note: Clearing client id will not affect the running state (e.g. field
+    // trial randomization), as the pref is only read on startup.
+    g_browser_process->local_state()->ClearPref(
+        metrics::prefs::kMetricsClientID);
+    g_browser_process->local_state()->ClearPref(
+        metrics::prefs::kMetricsReportingEnabledTimestamp);
+  }
+
   g_browser_process->GetMetricsServicesManager()->UpdatePermissions(
       may_record, may_upload);
 }
 
 // Renderer process crashed in the foreground.
 static void LogRendererCrash(JNIEnv*, const JavaParamRef<jclass>&) {
   DCHECK(g_browser_process);
   // Increment the renderer crash count in stability metrics.
   PrefService* pref = g_browser_process->local_state();
   DCHECK(pref);
@@ skipping 85 matching lines @@
   // We should have only one UmaSessionStats instance.
   DCHECK(!g_uma_session_stats);
   g_uma_session_stats = new UmaSessionStats();
   return reinterpret_cast<intptr_t>(g_uma_session_stats);
 }
 
 // Register native methods
 bool RegisterUmaSessionStats(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }