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

chrome/browser/dom_distiller/dom_distiller_viewer_source_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.h>
 
 #include "base/command_line.h"
 #include "base/guid.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/dom_distiller/dom_distiller_service_factory.h"
@@ skipping 69 matching lines @@
  public:
   DomDistillerViewerSourceBrowserTest() {}
   ~DomDistillerViewerSourceBrowserTest() override {}
 
   void SetUpOnMainThread() override {
     database_model_ = new FakeDB<ArticleEntry>::EntryMap;
   }
 
   void TearDownOnMainThread() override { delete database_model_; }
 
-  void SetUpCommandLine(CommandLine* command_line) override {
+  void SetUpCommandLine(base::CommandLine* command_line) override {
     command_line->AppendSwitch(switches::kEnableDomDistiller);
   }
 
   static KeyedService* Build(content::BrowserContext* context) {
     FakeDB<ArticleEntry>* fake_db = new FakeDB<ArticleEntry>(database_model_);
     distiller_factory_ = new MockDistillerFactory();
     MockDistillerPageFactory* distiller_page_factory_ =
         new MockDistillerPageFactory();
     DomDistillerContextKeyedService* service =
         new DomDistillerContextKeyedService(
@@ skipping 253 matching lines @@
   EXPECT_EQ("dark sans-serif", result);
 
   distilled_page_prefs->SetFontFamily(DistilledPagePrefs::SERIF);
   base::RunLoop().RunUntilIdle();
   EXPECT_TRUE(
       content::ExecuteScriptAndExtractString(contents, kGetBodyClass, &result));
   EXPECT_EQ("dark serif", result);
 }
 
 }  // namespace dom_distiller