Android: Remove unneeded RegisterNatives() calls

base/android/jni_generator/jni_generator.py

 #!/usr/bin/env python
 # 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.
 
 """Extracts native methods from a Java file and generates the JNI bindings.
 If you change this, please run and update the tests."""
 
 import collections
 import errno
@@ skipping 722 matching lines @@
 
 }  // namespace
 
 $OPEN_NAMESPACE
 
 $CONSTANT_FIELDS
 
 // Step 2: method stubs.
 $METHOD_STUBS
 
-// Step 3: RegisterNatives.

[Torne, 2016/08/01 11:51:41]

I don't think you should remove this comment - it makes files where "step 3" is
actually present look weird :)

 $JNI_NATIVE_METHODS
 $REGISTER_NATIVES
 $CLOSE_NAMESPACE
 
 #endif  // ${HEADER_GUARD}
 """)
     values = {
         'SCRIPT_NAME': self.options.script_name,
         'FULLY_QUALIFIED_CLASS': self.fully_qualified_class,
         'CLASS_PATH_DEFINITIONS': self.GetClassPathDefinitionsString(),
@@ skipping 68 matching lines @@
       return ''
     template = Template("""\
 static const JNINativeMethod kMethods${JAVA_CLASS}[] = {
 ${KMETHODS}
 };
 """)
     return self.SubstituteNativeMethods(template)
 
   def GetRegisterNativesString(self):
     """Returns the code for RegisterNatives."""
+    natives = self.GetRegisterNativesImplString()
+    if not natives:
+      return ''
+
     template = Template("""\
 ${REGISTER_NATIVES_SIGNATURE} {
 ${EARLY_EXIT}
 ${NATIVES}
   return true;
 }
 """)
     signature = 'static bool RegisterNativesImpl(JNIEnv* env)'
     early_exit = ''
     if self.options.native_exports_optional:
       early_exit = """\
   if (base::android::IsManualJniRegistrationDisabled()) return true;
 """
 
-    natives = self.GetRegisterNativesImplString()
     values = {'REGISTER_NATIVES_SIGNATURE': signature,
               'EARLY_EXIT': early_exit,
               'NATIVES': natives,
              }
     return template.substitute(values)
 
   def GetRegisterNativesImplString(self):
     """Returns the shared implementation for RegisterNatives."""
     if not self.options.native_exports_optional:
       return ''
@@ skipping 237 matching lines @@
 static ${RETURN_TYPE} Java_${JAVA_CLASS}_${METHOD_ID_VAR_NAME}(\
 JNIEnv* env${FIRST_PARAM_IN_DECLARATION}${PARAMS_IN_DECLARATION})""")
     function_header_template = Template("""\
 ${FUNCTION_SIGNATURE} {""")
     function_header_with_unused_template = Template("""\
 ${FUNCTION_SIGNATURE} __attribute__ ((unused));
 ${FUNCTION_SIGNATURE} {""")
     template = Template("""
 static base::subtle::AtomicWord g_${JAVA_CLASS}_${METHOD_ID_VAR_NAME} = 0;
 ${FUNCTION_HEADER}
-  /* Must call RegisterNativesImpl()  */

[Torne, 2016/08/01 11:51:41]

While it does make sense to remove this comment, can you do that in a followup
CL so that the changes to the golden test file are only the "functional" bits
and it's easy to see what actually changed about the code generation?

   CHECK_CLAZZ(env, ${FIRST_PARAM_IN_CALL},
       ${JAVA_CLASS}_clazz(env)${OPTIONAL_ERROR_RETURN});
   jmethodID method_id =
     ${GET_METHOD_ID_IMPL}
   ${RETURN_DECLARATION}
      ${PRE_CALL}env->${ENV_CALL}(${FIRST_PARAM_IN_CALL},
           method_id${PARAMS_IN_CALL})${POST_CALL};
   ${CHECK_EXCEPTION}
   ${RETURN_CLAUSE}
 }""")
@@ skipping 242 matching lines @@
   GenerateJNIHeader(input_file, output_file, options)
 
   if options.depfile:
     build_utils.WriteDepfile(
         options.depfile,
         build_utils.GetPythonDependencies())
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))