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

chrome/browser/extensions/signin/gaia_auth_extension_loader.cc

Index: chrome/browser/extensions/signin/gaia_auth_extension_loader.cc
diff --git a/chrome/browser/extensions/signin/gaia_auth_extension_loader.cc b/chrome/browser/extensions/signin/gaia_auth_extension_loader.cc
index 4766862cecaa22932f361e09d149eb9043b6fa1f..c636b897bd049e72e700bc397064ac7d692ecd8f 100644
--- a/chrome/browser/extensions/signin/gaia_auth_extension_loader.cc
+++ b/chrome/browser/extensions/signin/gaia_auth_extension_loader.cc
@@ -40,7 +40,8 @@ void LoadGaiaAuthExtension(BrowserContext* context) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   extensions::ComponentLoader* component_loader = GetComponentLoader(context);
-  const CommandLine* command_line = CommandLine::ForCurrentProcess();
+  const base::CommandLine* command_line =
+      base::CommandLine::ForCurrentProcess();
   if (command_line->HasSwitch(switches::kAuthExtensionPath)) {
     base::FilePath auth_extension_path =
         command_line->GetSwitchValuePath(switches::kAuthExtensionPath);