Add retrolambda.py and integrate it to build process.

build/config/android/rules.gni

 # Copyright 2014 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.
 
 # Do not add any imports to non-//build directories here.
 # Some projects (e.g. V8) do not have non-build directories DEPS'ed in.
 import("//build/config/android/config.gni")
 import("//build/config/android/internal_rules.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/dcheck_always_on.gni")
@@ skipping 1142 matching lines @@
     }
   }
 
   # Declare a java library target for a prebuilt jar
   #
   # Variables
   #   deps: Specifies the dependencies of this target. Java targets in this list
   #     will be added to the javac classpath.
   #   jar_path: Path to the prebuilt jar.
   #   jar_dep: Target that builds jar_path (optional).
+  #   main_class: When specified, a wrapper script is created within
+  #     $root_build_dir/bin to launch the binary with the given class as the
+  #     entrypoint.
   #   output_name: File name for the output .jar (not including extension).
   #     Defaults to the input .jar file name.
   #   proguard_preprocess: If true, proguard preprocessing will be run. This can
   #     be used to remove unwanted parts of the library.
   #   proguard_preprocess_config: Path to the proguard config for preprocessing.
   #   proguard_configs: List of proguard configs to use in final apk step for
   #     any apk that depends on this library.
   #   supports_android: If true, Android targets (android_library, android_apk)
   #     may depend on this target. Note: if true, this target must only use the
   #     subset of Java available on Android.
@@ skipping 1588 matching lines @@
         # because in practice they seem to contain classes required to be in the
         # classpath.
         deps += _subjar_targets
       }
       if (defined(_res_target_name)) {
         deps += [ ":$_res_target_name" ]
       }
     }
   }
 }