extensions: Use stl utilities from the base namespace

extensions/browser/content_verifier.cc

Index: extensions/browser/content_verifier.cc
diff --git a/extensions/browser/content_verifier.cc b/extensions/browser/content_verifier.cc
index c47db07826f2fdec20cd6b3fa03ebab6a725b50c..58a899780bf147f1f955412bf5bd2188b7756194 100644
--- a/extensions/browser/content_verifier.cc
+++ b/extensions/browser/content_verifier.cc
@@ -261,7 +261,7 @@ bool ContentVerifier::ShouldVerifyAnyPaths(
     if (relative_path == base::FilePath(kManifestFilename))
       continue;
 
-    if (ContainsKey(browser_images, relative_path))
+    if (base::ContainsKey(browser_images, relative_path))
       continue;
 
     base::FilePath full_path = extension_root.Append(relative_path);