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

chrome/browser/chrome_browser_main_mac.mm

Index: chrome/browser/chrome_browser_main_mac.mm
diff --git a/chrome/browser/chrome_browser_main_mac.mm b/chrome/browser/chrome_browser_main_mac.mm
index bfbe7eae4e377c560e70877d4d09b3c8fae05b53..2dc68c85646d84bccf8cb91d1eeb6ba0025563fe 100644
--- a/chrome/browser/chrome_browser_main_mac.mm
+++ b/chrome/browser/chrome_browser_main_mac.mm
@@ -165,10 +165,12 @@ void ChromeBrowserMainPartsMac::PreEarlyInitialization() {
   ChromeBrowserMainPartsPosix::PreEarlyInitialization();
 
   if (base::mac::WasLaunchedAsLoginItemRestoreState()) {
-    CommandLine* singleton_command_line = CommandLine::ForCurrentProcess();
+    base::CommandLine* singleton_command_line =
+        base::CommandLine::ForCurrentProcess();
     singleton_command_line->AppendSwitch(switches::kRestoreLastSession);
   } else if (base::mac::WasLaunchedAsHiddenLoginItem()) {
-    CommandLine* singleton_command_line = CommandLine::ForCurrentProcess();
+    base::CommandLine* singleton_command_line =
+        base::CommandLine::ForCurrentProcess();
     singleton_command_line->AppendSwitch(switches::kNoStartupWindow);
   }