Resetting metrics ids on clump detection.

chrome/browser/metrics/metrics_service_unittest.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 "chrome/browser/metrics/metrics_service.h"
 
 #include <ctype.h>
 #include <string>
 
 #include "base/command_line.h"
@@ skipping 356 matching lines @@
   GetLocalState()->SetBoolean(crash_pref, true);
   EXPECT_TRUE(MetricsServiceHelper::IsCrashReportingEnabled());
   GetLocalState()->ClearPref(crash_pref);
   EXPECT_FALSE(MetricsServiceHelper::IsCrashReportingEnabled());
 #endif // !defined(OS_CHROMEOS)
 #else // defined(GOOGLE_CHROME_BUILD)
   // Chromium branded browsers never have crash reporting enabled.
   EXPECT_FALSE(MetricsServiceHelper::IsCrashReportingEnabled());
 #endif // defined(GOOGLE_CHROME_BUILD)
 }
+
+// Check that setting the kMetricsResetIds pref to true causes the client id to
+// be reset. We do not check that the low entropy source is reset because we
+// cannot ensure that metrics service won't generate the same id again.
+TEST_F(MetricsServiceTest, ResetMetricsIDs) {
+  // Set an initial client id in prefs. It should not be possible for the
+  // metrics service to generate this id randomly.
+  const std::string kInitialClientId = "initial client id";
+  GetLocalState()->SetString(prefs::kMetricsClientID, kInitialClientId);
+
+  // Make sure the initial client id isn't reset by the metrics service.
+  {
+    MetricsService service;
+    service.ForceClientIdCreation();
+    EXPECT_TRUE(service.metrics_ids_reset_check_performed_);
+    EXPECT_EQ(kInitialClientId, service.client_id_);
+  }
+
+
+  // Set the reset pref to cause the IDs to be reset.
+  GetLocalState()->SetBoolean(prefs::kMetricsResetIds, true);
+
+  // Cause the actual reset to happen.
+  {
+    MetricsService service;
+    service.ForceClientIdCreation();
+    EXPECT_TRUE(service.metrics_ids_reset_check_performed_);
+    EXPECT_NE(kInitialClientId, service.client_id_);
+
+    service.GetLowEntropySource();
+
+    EXPECT_FALSE(GetLocalState()->GetBoolean(prefs::kMetricsResetIds));
+  }
+
+  std::string new_client_id =
+      GetLocalState()->GetString(prefs::kMetricsClientID);
+
+  EXPECT_NE(kInitialClientId, new_client_id);
+}