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

chrome/browser/first_run/first_run_browsertest.cc

Index: chrome/browser/first_run/first_run_browsertest.cc
diff --git a/chrome/browser/first_run/first_run_browsertest.cc b/chrome/browser/first_run/first_run_browsertest.cc
index b32baa128c1b705ac504ad6d69d5a1fcbca8212c..ebcf208799a491882d5887e3c89b8d57df1b1256 100644
--- a/chrome/browser/first_run/first_run_browsertest.cc
+++ b/chrome/browser/first_run/first_run_browsertest.cc
@@ -101,7 +101,7 @@ class FirstRunMasterPrefsBrowserTestBase : public InProcessBrowserTest {
     InProcessBrowserTest::TearDown();
   }
 
-  void SetUpCommandLine(CommandLine* command_line) override {
+  void SetUpCommandLine(base::CommandLine* command_line) override {
     InProcessBrowserTest::SetUpCommandLine(command_line);
     command_line->AppendSwitch(switches::kForceFirstRun);
     EXPECT_EQ(first_run::AUTO_IMPORT_NONE, first_run::auto_import_state());
@@ -247,7 +247,7 @@ class FirstRunMasterPrefsWithTrackedPreferences
     : public FirstRunMasterPrefsBrowserTestT<kWithTrackedPrefs>,
       public testing::WithParamInterface<std::string> {
  public:
-  void SetUpCommandLine(CommandLine* command_line) override {
+  void SetUpCommandLine(base::CommandLine* command_line) override {
     FirstRunMasterPrefsBrowserTestT::SetUpCommandLine(command_line);
     command_line->AppendSwitchASCII(
         switches::kForceFieldTrials,