Make callers of CommandLine use it via the base:: namespace.

chrome/browser/prefs/tracked/pref_hash_browsertest.cc

 // Copyright 2014 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 <string>
 
 #include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/json/json_file_value_serializer.h"
@@ skipping 129 matching lines @@
     PROTECTION_ENABLED_EXTENSIONS,
     // Represents the strongest level (i.e. always equivalent to the last one in
     // terms of protection), leave this one last when adding new levels.
     PROTECTION_ENABLED_ALL
   };
 
   PrefHashBrowserTestBase()
       : protection_level_(GetProtectionLevelFromTrialGroup(GetParam())) {
   }
 
-  void SetUpCommandLine(CommandLine* command_line) override {
+  void SetUpCommandLine(base::CommandLine* command_line) override {
     ExtensionBrowserTest::SetUpCommandLine(command_line);
     EXPECT_FALSE(command_line->HasSwitch(switches::kForceFieldTrials));
     command_line->AppendSwitchASCII(
         switches::kForceFieldTrials,
         std::string(chrome_prefs::internals::kSettingsEnforcementTrialName) +
             "/" + GetParam() + "/");
 #if defined(OS_CHROMEOS)
     command_line->AppendSwitch(
         chromeos::switches::kIgnoreUserProfileMappingForTests);
 #endif
@@ skipping 749 matching lines @@
                   "Settings.TrackedPreferenceNullInitialized", ALLOW_NONE));
     EXPECT_EQ(
         0,
         GetTrackedPrefHistogramCount(
             "Settings.TrackedPreferenceMigratedLegacyDeviceId", ALLOW_NONE));
   }
 };
 
 PREF_HASH_BROWSER_TEST(PrefHashBrowserTestUntrustedAdditionToPrefsAfterWipe,
                        UntrustedAdditionToPrefsAfterWipe);