experiment with -Wimplicit-fallthrough

google_apis/gaia/oauth_request_signer.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "google_apis/gaia/oauth_request_signer.h"
 
 #include <cctype>
 #include <cstddef>
 #include <cstdlib>
 #include <cstring>
@@ skipping 391 matching lines @@
   DCHECK(request_base_url.is_valid());
   Parameters parameters(request_parameters);
   bool is_signed = SignParameters(request_base_url, signature_method,
                                   http_method, consumer_key, consumer_secret,
                                   token_key, token_secret, &parameters);
   if (is_signed) {
     std::string signed_text;
     switch (http_method) {
       case GET_METHOD:
         signed_text = request_base_url.spec() + '?';
-        // Intentionally falling through
+        FALLTHROUGH_INTENDED;
       case POST_METHOD:
         signed_text += BuildBaseStringParameters(parameters);
         break;
       default:
         NOTREACHED();
     }
     *signed_text_return = signed_text;
   }
   return is_signed;
 }
@@ skipping 27 matching lines @@
       signed_text +=
           base::StringPrintf(
               "%s=\"%s\"",
               OAuthRequestSigner::Encode(param->first).c_str(),
               OAuthRequestSigner::Encode(param->second).c_str());
     }
     *signed_text_return = signed_text;
   }
   return is_signed;
 }