[WIP] Remove unneeded JNI registrations.

base/android/jni_generator/jni_generator.py

Index: base/android/jni_generator/jni_generator.py
diff --git a/base/android/jni_generator/jni_generator.py b/base/android/jni_generator/jni_generator.py
index de865d527be81e9afda60a5d866e9b3aa81f4f8e..b2d8013b12bc5fe242fa577bf4d71fabba4097e5 100755
--- a/base/android/jni_generator/jni_generator.py
+++ b/base/android/jni_generator/jni_generator.py
@@ -599,10 +599,12 @@ $CLASS_PATH_DEFINITIONS
 }  // namespace
 
 $OPEN_NAMESPACE
+extern "C"{
 $FORWARD_DECLARATIONS
 
 // Step 2: method stubs.
 $METHOD_STUBS
+};
 
 // Step 3: RegisterNatives.
 
@@ -660,6 +662,8 @@ $CLOSE_NAMESPACE
 
   def GetRegisterNativesImplString(self):
     """Returns the implementation for RegisterNatives."""
+    if not self.called_by_natives:
+      return ''
     template = Template("""\
   static const JNINativeMethod kMethods${JAVA_CLASS}[] = {
 ${KMETHODS}
@@ -681,7 +685,7 @@ ${KMETHODS}
       if kmethods:
         values = {'JAVA_CLASS': clazz,
                   'KMETHODS': kmethods}
-        ret += [template.substitute(values)]
+    #    ret += [template.substitute(values)]
     if not ret: return ''
     return '\n' + '\n'.join(ret)
 
@@ -733,9 +737,17 @@ ${KMETHODS}
   def GetForwardDeclaration(self, native):
     template = Template("""
 static ${RETURN} ${NAME}(JNIEnv* env, ${PARAMS});
+__attribute__((visibility("default"))) ${RETURN}
+    Java_${JAVA_NAME}_native${NAME}(JNIEnv* env, ${PARAMS})
+        __attribute__((alias("${NAME}")));

[bulach, 2013/06/28 00:45:54]

I think you can combine the attributes:
__attribute__((alias("${NAME}"), visibility("default")))

 """)
+    java_name = JniParams.RemapClassName(self.fully_qualified_class).replace('_', '_1').replace('/', '_')
+    if native.java_class_name:
+      java_name += "_00024" + native.java_class_name
+
     values = {'RETURN': JavaDataTypeToC(native.return_type),
               'NAME': native.name,
+              'JAVA_NAME': java_name,
               'PARAMS': self.GetParamsInDeclaration(native)}
     return template.substitute(values)
 
@@ -747,6 +759,8 @@ static ${RETURN} ${NAME}(JNIEnv* env, ${PARAMS_IN_DECLARATION}) {
   ${P0_TYPE}* native = reinterpret_cast<${P0_TYPE}*>(${PARAM0_NAME});
   return native->${NAME}(env, obj${PARAMS_IN_CALL})${POST_CALL};
 }
+__attribute__((visibility("default"))) ${RETURN} Java_${JAVA_NAME}_native${NAME}(JNIEnv* env,
+  ${PARAMS_IN_DECLARATION}) __attribute__((alias("${NAME}")));
 """)
     params_for_call = ', '.join(p.name for p in native.params[1:])
     if params_for_call:
@@ -759,9 +773,14 @@ static ${RETURN} ${NAME}(JNIEnv* env, ${PARAMS_IN_DECLARATION}) {
     else:
       scoped_return_type = return_type
       post_call = ''
+    java_name = JniParams.RemapClassName(self.fully_qualified_class).replace('_', '_1').replace('/', '_')
+    if native.java_class_name:
+      java_name += "_00024" + native.java_class_name
+
     values = {
         'RETURN': return_type,
         'SCOPED_RETURN': scoped_return_type,
+        'JAVA_NAME': java_name,
         'NAME': native.name,
         'PARAMS_IN_DECLARATION': self.GetParamsInDeclaration(native),
         'PARAM0_NAME': native.params[0].name,
@@ -879,12 +898,11 @@ ${FUNCTION_HEADER}
   def GetClassPathDefinitions(self):
     """Returns the ClassPath constants."""
     ret = []
+    if not self.called_by_natives:
+      return ''
     template = Template("""\
 const char k${JAVA_CLASS}ClassPath[] = "${JNI_CLASS_PATH}";""")
-    native_classes = self.GetUniqueClasses(self.natives)
-    called_by_native_classes = self.GetUniqueClasses(self.called_by_natives)
-    all_classes = native_classes
-    all_classes.update(called_by_native_classes)
+    all_classes = self.GetUniqueClasses(self.called_by_natives)
     for clazz in all_classes:
       values = {
           'JAVA_CLASS': clazz,
@@ -892,7 +910,7 @@ const char k${JAVA_CLASS}ClassPath[] = "${JNI_CLASS_PATH}";""")
       }
       ret += [template.substitute(values)]
     ret += ''
-    for clazz in called_by_native_classes:
+    for clazz in all_classes:
       template = Template("""\
 // Leaking this jclass as we cannot use LazyInstance from some threads.
 jclass g_${JAVA_CLASS}_clazz = NULL;""")