Cleanup: Better constify some strings in chrome/browser/{chromeos,extensions}.

chrome/browser/extensions/api/proxy/proxy_api_constants.h

Index: chrome/browser/extensions/api/proxy/proxy_api_constants.h
diff --git a/chrome/browser/extensions/api/proxy/proxy_api_constants.h b/chrome/browser/extensions/api/proxy/proxy_api_constants.h
index 6dc64d1657667a79754911b834b8d490ead7b553..69f70933cdd2a5b49b43926962d96bd9296d3306 100644
--- a/chrome/browser/extensions/api/proxy/proxy_api_constants.h
+++ b/chrome/browser/extensions/api/proxy/proxy_api_constants.h
@@ -43,12 +43,12 @@ enum {
 
 // The names of the JavaScript properties to extract from the proxy_rules.
 // These must be kept in sync with the SCHEME_* constants.
-extern const char* field_name[];
+extern const char* const field_name[];
 
 // The names of the schemes to be used to build the preference value string
 // for manual proxy settings.  These must be kept in sync with the SCHEME_*
 // constants.
-extern const char* scheme_name[];
+extern const char* const scheme_name[];
 
 }  // namespace proxy_api_constants
 }  // namespace extensions