Move kFileScheme constant into content namespace.

extensions/common/url_pattern_set.cc

Index: extensions/common/url_pattern_set.cc
diff --git a/extensions/common/url_pattern_set.cc b/extensions/common/url_pattern_set.cc
index 1d294974413eedc8e9cfdd05aab138e1bcc7348c..81872991790639a59a50fb05186b6a359906eb45 100644
--- a/extensions/common/url_pattern_set.cc
+++ b/extensions/common/url_pattern_set.cc
@@ -206,7 +206,7 @@ bool URLPatternSet::Populate(const std::vector<std::string>& patterns,
       }
       return false;
     }
-    if (!allow_file_access && pattern.MatchesScheme(chrome::kFileScheme)) {
+    if (!allow_file_access && pattern.MatchesScheme(content::kFileScheme)) {
       pattern.SetValidSchemes(
           pattern.valid_schemes() & ~URLPattern::SCHEME_FILE);
     }