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

chrome/browser/extensions/api/file_system/file_system_apitest.cc

Index: chrome/browser/extensions/api/file_system/file_system_apitest.cc
diff --git a/chrome/browser/extensions/api/file_system/file_system_apitest.cc b/chrome/browser/extensions/api/file_system/file_system_apitest.cc
index 9b60f919752f0b90221d8bfd9b8fd8d0c64db2ac..a9cadbcf87be110c4fd6da9475c1bc9a0cb97470 100644
--- a/chrome/browser/extensions/api/file_system/file_system_apitest.cc
+++ b/chrome/browser/extensions/api/file_system/file_system_apitest.cc
@@ -64,7 +64,7 @@ const int kGraylistedPath = base::DIR_HOME;
 
 class FileSystemApiTest : public PlatformAppBrowserTest {
  public:
-  void SetUpCommandLine(CommandLine* command_line) override {
+  void SetUpCommandLine(base::CommandLine* command_line) override {
     PlatformAppBrowserTest::SetUpCommandLine(command_line);
     test_root_folder_ = test_data_dir_.AppendASCII("api_test")
         .AppendASCII("file_system");