Update experimental Java 8 support to use Desugar instead of Retrolambda

build/config/android/internal_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_overrides/build.gni")
 import("//build/config/android/config.gni")
 import("//build/config/dcheck_always_on.gni")
 import("//build/config/sanitizers/sanitizers.gni")
@@ skipping 1163 matching lines @@
       _jar_excluded_patterns = invoker.jar_excluded_patterns
     }
     _strip_resource_classes = defined(invoker.strip_resource_classes) &&
                               invoker.strip_resource_classes
     _filter_jar = _jar_excluded_patterns != [] || _strip_resource_classes
 
     _enable_assert =
         defined(invoker.supports_android) && invoker.supports_android &&
         (is_java_debug || dcheck_always_on)
 
+    #TODO(zpeng): Remove Retrolambda when Desugar is enabled.

[agrieve, 2017/07/20 00:26:52]

Can we do this now rather than checking in an if (false) statement?

[F, 2017/07/20 17:30:56]

Done.

     _retrolambda =
         defined(invoker.supports_android) && invoker.supports_android &&
         ((defined(invoker.process_java8) && invoker.process_java8) || use_java8)
 
+    _desugar = false &&
+        defined(invoker.supports_android) && invoker.supports_android &&
+        ((defined(invoker.process_java8) && invoker.process_java8) || use_java8)
+  
     _deps = []
     _previous_output_jar = _input_jar_path
 
     if (_filter_jar) {
       _filter_target = "${target_name}__filter"
       _filter_input_jar = _previous_output_jar
       _filter_output_jar = "$target_out_dir/$target_name-filtered.jar"
 
       action(_filter_target) {
         script = "//build/android/gyp/jar.py"
@@ skipping 93 matching lines @@
           "--android-sdk-jar",
           rebase_path(android_sdk_jar, root_build_dir),
         ]
       }
 
       _deps = []
       _deps = [ ":$_retrolambda_target" ]
       _previous_output_jar = _retrolambda_output_jar
     }
 
+    if (_desugar) {
+      _desugar_target = "${target_name}__desugar"
+      _desugar_input_jar = _previous_output_jar
+      _desugar_output_jar = "$target_out_dir/$target_name-desugar.jar"
+
+      android_sdk_jar = "$android_sdk/android.jar"
+      action(_desugar_target) {
+        script = "//build/android/gyp/desugar.py"
+        deps = _deps
+        if (defined(invoker.deps)) {
+          deps += invoker.deps
+        }
+        if (defined(invoker.public_deps)) {
+          public_deps = invoker.public_deps
+        }
+        inputs = [
+          _build_config,
+          _desugar_input_jar,
+        ]
+        outputs = [
+          _desugar_output_jar,
+        ]
+        if (defined(invoker.alternative_android_sdk_ijar)) {
+          deps += [ invoker.alternative_android_sdk_ijar_dep ]
+          _android_sdk_ijar = invoker.alternative_android_sdk_ijar
+        } else {
+          deps += [ "//build/android:android_ijar" ]
+          _android_sdk_ijar = "$root_out_dir/lib.java/android.interface.jar"
+        }
+        inputs += [ _android_sdk_ijar ]
+        args = [
+          "--input-jar",
+          rebase_path(_desugar_input_jar, root_build_dir),
+          "--output-jar",
+          rebase_path(_desugar_output_jar, root_build_dir),
+          "--classpath=@FileArg($_rebased_build_config:javac:classpath)",
+          "--android-sdk-jar",
+          rebase_path(android_sdk_jar, root_build_dir),
+          "--bootclasspath",
+          rebase_path(_android_sdk_ijar, root_build_dir),
+        ]
+      }
+
+      _deps = []
+      _deps = [ ":$_desugar_target" ]
+      _previous_output_jar = _desugar_output_jar
+    }
+    
     _output_jar_target = "${target_name}__copy"
     copy(_output_jar_target) {
       deps = _deps
       if (defined(invoker.deps)) {
         deps += invoker.deps
       }
       if (defined(invoker.public_deps)) {
         public_deps = invoker.public_deps
       }
       sources = [
@@ skipping 730 matching lines @@
         # Use original jar_path because _jar_path points to a library without
         # resources.
         java_resources_jar = invoker.jar_path
       }
     }
 
     process_java_prebuilt(_process_jar_target_name) {
       forward_variables_from(invoker,
                              [
                                "jar_excluded_patterns",
+                               "process_java8",
                                "strip_resource_classes",
-                               "process_java8",
                              ])
 
       visibility = [
         ":$_ijar_target_name",
         ":$_template_name",
       ]
       if (_supports_android) {
         visibility += [ ":$_dex_target_name" ]
       }
 
@@ skipping 271 matching lines @@
         inputs += [ file_tuple[0] ]
         args +=
             [ "--additional-jar-file=" + file_tuple[0] + ":" + file_tuple[1] ]
       }
       if (invoker.java_files != []) {
         args += [ "@" + rebase_path(invoker.java_sources_file, root_build_dir) ]
       }
     }
 
     process_java_prebuilt(_process_prebuilt_target_name) {
-      forward_variables_from(invoker, [ "jar_excluded_patterns" ])
+      forward_variables_from(invoker,
+                             [
+                               "alternative_android_sdk_ijar",
+                               "alternative_android_sdk_ijar_dep",
+                               "jar_excluded_patterns",
+                             ])
       supports_android = _supports_android
       build_config = _build_config
       input_jar_path = _javac_jar_path
       output_jar_path = _process_prebuilt_jar_path
 
       deps = [
         ":$_javac_target_name",
       ]
       if (defined(invoker.deps)) {
         deps += invoker.deps
@@ skipping 621 matching lines @@
         rebase_path(root_build_dir, root_build_dir),
         "--packed-libraries-dir",
         rebase_path(_packed_libraries_dir, root_build_dir),
         "--libraries=${invoker.libraries_filearg}",
         "--filelistjson",
         rebase_path(invoker.file_list_json, root_build_dir),
       ]
     }
   }
 }