Make the build control what library(/ies) to load

build/android/java_cpp_template.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 generate Java source files from templates that are processed
 # through the host C pre-processor.
 #
 # To use this, create a gyp target with the following form:
 #  {
 #    'target_name': 'android_net_java_constants',
 #    'type': 'none',
 #    'sources': [
 #      'net/android/NetError.template',
 #    ],
 #    'variables': {
 #      'package_name': 'org/chromium/net',
 #      'template_deps': ['net/base/certificate_mime_type_list.h'],
 #    },
-#    'includes': [ '../build/android/java_constants.gypi' ],
+#    'includes': [ '../build/android/java_cpp_template.gypi' ],
 #  },
 #
 # The 'sources' entry should only list template file. The template file
 # itself should use the 'ClassName.template' format, and will generate
 # 'gen/templates/<package-name>/ClassName.java. The files which template
 # dependents on and typically included by the template should be listed
 # in template_deps variables. Any change to them will force a rebuild of
 # the template, and hence of any source that depends on it.
 #
 
 {
   # Location where all generated Java sources will be placed.
   'variables': {
-    'output_dir': '<(SHARED_INTERMEDIATE_DIR)/templates/<(package_name)'
+    'include_path%': '<(DEPTH)',
+    'output_dir': '<(SHARED_INTERMEDIATE_DIR)/templates/<(package_name)',
   },
   # Ensure that the output directory is used in the class path
   # when building targets that depend on this one.
   'direct_dependent_settings': {
     'variables': {
       'generated_src_dirs': [
         '<(output_dir)/',
       ],
     },
   },
   # Define a single rule that will be apply to each .template file
   # listed in 'sources'.
   'rules': [
     {
       'rule_name': 'generate_java_constants',
       'extension': 'template',
       # Set template_deps as additional dependencies.
-      'inputs': ['<@(template_deps)'],
+      'variables': {
+        'output_path': '<(output_dir)/<(RULE_INPUT_ROOT).java',
+      },
+      'inputs': [
+        '<(DEPTH)/build/android/pylib/build_utils.py',
+        '<(DEPTH)/build/android/gcc_preprocess.py',
+        '<@(template_deps)'
+      ],
       'outputs': [
-        '<(output_dir)/<(RULE_INPUT_ROOT).java'
+        '<(output_path)',
       ],
       'action': [
-        'gcc',                 # invoke host gcc.
-        '-E',                  # stop after preprocessing.
-        '-D', 'ANDROID',       # Specify ANDROID define for pre-processor.
-        '-x', 'c-header',      # treat sources as C header files
-        '-P',                  # disable line markers, i.e. '#line 309'
-        '-I', '<(DEPTH)',      # Add project top-level to include path
-        '-o', '<@(_outputs)',  # Specify output file
-        '<(RULE_INPUT_PATH)',  # Specify input file
+        'python', '<(DEPTH)/build/android/gcc_preprocess.py',
+        '--include-path=<(include_path)',
+        '--output=<(output_path)',
+        '--template=<(RULE_INPUT_PATH)',
       ],
       'message': 'Generating Java from cpp template <(RULE_INPUT_PATH)',
     }
   ],
 }