Add more generic support for java targets bundling multiple directories

build/java.gypi

 # 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.
 
 # This file is meant to be included into a target to provide a rule
 # to build Java in a consistent manner.
 #
 # To use this, create a gyp target with the following form:
 # {
 #   'target_name': 'my-package_java',
 #   'type': 'none',
 #   'variables': {
 #     'package_name': 'my-package',
 #     'java_in_dir': 'path/to/package/root',
 #   },
 #   'includes': ['path/to/this/gypi/file'],
 # }
 #
-# Note that this assumes that there's ant buildfile with package_name in
-# java_in_dir. So if if you have package_name="base" and
-# java_in_dir="base/android/java" you should have a directory structure like:
+# The generated jar-file will be:
+#   <(PRODUCT_DIR)/lib.java/chromium_<(package_name).jar
 #
-# base/android/java/base.xml
-# base/android/java/org/chromium/base/Foo.java
-# base/android/java/org/chromium/base/Bar.java
-#
-# Finally, the generated jar-file will be:
-#   <(PRODUCT_DIR)/lib.java/chromium_base.jar
+# Required variables:
+#  package_name - Used to name the intermediate output directory and in the
+#    names of some output files.
+#  java_in_dir - The top-level java directory. The src should be in
+#    <java_in_dir>/src.
+# Optional/automatic variables:
+#  additional_input_paths - These paths will be included in the 'inputs' list to
+#    ensure that this target is rebuilt when one of these paths changes.
+#  additional_src_dirs - Additional directories with .java files to be compiled
+#    and included in the output of this target.
+#  generated_src_dirs - Same as additional_src_dirs except used for .java files
+#    that are generated at build time. This should be set automatically by a
+#    target's dependencies. The .java files in these directories are not
+#    included in the 'inputs' list (unlike additional_src_dirs).
+#  input_jars_paths - The path to jars to be included in the classpath. This
+#    should be filled automatically by depending on the appropriate targets.
 
 {
   'dependencies': [
     '<(DEPTH)/build/build_output_dirs_android.gyp:build_output_dirs'
   ],
   'direct_dependent_settings': {
     'variables': {
       'input_jars_paths': ['<(PRODUCT_DIR)/lib.java/chromium_<(package_name).jar'],
     },
   },
   'variables': {
     'input_jars_paths': [],
     'additional_src_dirs': [],
     'additional_input_paths': [],
+    'generated_src_dirs': [],
   },
   'actions': [
     {
       'action_name': 'ant_<(package_name)',
       'message': 'Building <(package_name) java sources.',
       'inputs': [
         'android/ant/common.xml',
         'android/ant/chromium-jars.xml',
-        '<!@(find <(java_in_dir) -name "*.java")',
+        '>!@(find >(java_in_dir) >(additional_src_dirs) -name "*.java")',
         '>@(input_jars_paths)',
         '>@(additional_input_paths)',
       ],
       'outputs': [
         '<(PRODUCT_DIR)/lib.java/chromium_<(package_name).jar',
       ],
       'action': [
         'ant',
-        '-DPRODUCT_DIR=<(ant_build_out)',
-        '-DPACKAGE_NAME=<(package_name)',
-        '-DINPUT_JARS_PATHS=>(input_jars_paths)',
-        '-DADDITIONAL_SRC_DIRS=>(additional_src_dirs)',
         '-DANDROID_SDK=<(android_sdk)',
         '-DANDROID_SDK_ROOT=<(android_sdk_root)',
         '-DANDROID_SDK_TOOLS=<(android_sdk_tools)',
         '-DANDROID_SDK_VERSION=<(android_sdk_version)',
         '-DANDROID_GDBSERVER=<(android_gdbserver)',
+        '-DPRODUCT_DIR=<(ant_build_out)',
+
+        '-DADDITIONAL_SRC_DIRS=>(additional_src_dirs)',
+        '-DGENERATED_SRC_DIRS=>(generated_src_dirs)',
+        '-DINPUT_JARS_PATHS=>(input_jars_paths)',
+        '-DPACKAGE_NAME=<(package_name)',
+
         '-Dbasedir=<(java_in_dir)',
         '-buildfile',
         '<(DEPTH)/build/android/ant/chromium-jars.xml'
       ]
     },
   ],
 }