Add support for generating jars from protos and add cacheinvalidation_java.

build/protoc_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 invoke protoc in a consistent manner. This is only to be included
+# for Java targets. When including this file, a .jar-file will be generated.
+# For other targets, see protoc.gypi.
+#
+# To use this, create a gyp target with the following form:
+# {
+#   'target_name': 'my_proto_lib',
+#   'sources': [
+#     'foo.proto',
+#     'bar.proto',
+#   ],
+#   'variables': {
+#     'proto_in_dir': '.'
+#   },
+#   'includes': ['path/to/this/gypi/file'],
+# }
+#
+# The 'proto_in_dir' variable must be the relative path to the
+# directory containing the .proto files.  If left out, it defaults to '.'.
+#
+# The 'output_java_files' variable specifies a list of output files that will
+# be generated. It is based on the package and java_outer_classname fields in
+# the proto. All the values must be prefixed with >(java_out_dir), since that
+# is the root directory of all the output.
+#
+# Implementation notes:
+# A target_name of foo and proto-specified 'package' java.package.path produces:
+#   <(PRODUCT_DIR)/javaproto/foo/{java/package/path/}{Foo,Bar}.java
+# where Foo and Bar are taken from 'java_outer_classname' of the protos.
+#
+# How the .jar-file is created is different than how protoc is used for other
+# targets, and as such, this lives in its own file.
+
+{
+  'variables': {
+    'protoc': '<(PRODUCT_DIR)/<(EXECUTABLE_PREFIX)protoc<(EXECUTABLE_SUFFIX)',
+    'java_out_dir': '<(PRODUCT_DIR)/javaproto/<(_target_name)/src',
+    'proto_in_dir%': '.',
+    # Variables needed by java.gypi below.
+    'package_name': '<(_target_name)',
+    'java_in_dir': '<(DEPTH)/build/android/empty',
+    'stamp_file': '<(java_out_dir).stamp',
+    'script': '<(DEPTH)/build/protoc_java.sh',

[Ryan Sleevi, 2012/10/30 00:50:43]

I think I would be happier if this were (cross-platform) Python rather than
Bash, but I can live with it. I thought maruel and scottmg were trying to kill
off bash-in-build-scripts, but that may have only related to shared code.

Something to consider, at least.

[nyquist, 2012/10/31 17:49:33]

Done.

+    'generated_src_dirs': ['<(java_out_dir)'],
+  },
+  'actions': [
+    {
+      'action_name': 'genproto_java',
+      'inputs': [
+        '<(script)',
+        '<(protoc)',
+        '<@(_sources)',
+      ],
+      # We do not know the names of the generated files, so we use a stamp.
+      'outputs': [
+        '<(stamp_file)',
+      ],
+      'action': [
+        '<(script)',
+        '<(protoc)',
+        '<(proto_in_dir)',
+        '<(java_out_dir)',
+        '<(stamp_file)',
+        '<@(_sources)',
+      ],
+      'message': 'Generating Java code from <(proto_in_dir)',
+    },
+  ],
+  'dependencies': [
+    '<(DEPTH)/third_party/protobuf/protobuf.gyp:protoc#host',
+    '<(DEPTH)/third_party/protobuf/protobuf.gyp:protobuf_lite_java',
+  ],
+  'includes': [ 'java.gypi' ],
+}