Revert of [Service Manager] Get rid of dynamic service discovery

services/service_manager/public/cpp/service.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.
 
 import("//build/toolchain/toolchain.gni")
+import("//services/service_manager/public/constants.gni")
 
 if (is_android) {
   import("//build/config/android/rules.gni")
   import("//build/config/zip.gni")
 }
 
-# Generates a Service binary. The parameters of this template are those of an
-# executable.
+# Generates a Service "package", which includes:
+#
+#   - A self-named subdirectory
+#   - A binary .service executable
+#   - A resources subdirectory alongside the executable, which contains the
+#     contents of "resources"
+#
+# The parameters of this template are those of an executable
 template("service") {
   base_target_name = target_name
   if (defined(invoker.output_name)) {
     base_target_name = invoker.output_name
   }
 
+  final_target_name = target_name
+
   service_deps = []
   if (defined(invoker.deps)) {
     service_deps += invoker.deps
   }
 
   service_data_deps =
       [ "//services/service_manager/public/cpp/standalone_service:main" ]
 
+  if (defined(invoker.resources)) {
+    copy_step_name = "${base_target_name}__copy_resources"
+    copy(copy_step_name) {
+      sources = invoker.resources
+      outputs = [
+        "${root_out_dir}/${packages_directory}/${base_target_name}/resources/{{source_file_part}}",
+      ]
+      if (defined(invoker.testonly)) {
+        testonly = invoker.testonly
+      }
+      deps = service_deps
+    }
+    service_data_deps += [ ":$copy_step_name" ]
+  }
+
   if (defined(invoker.data_deps)) {
     service_data_deps += invoker.data_deps
   }
 
-  if (defined(invoker.resources)) {
-    # TODO(rockot): Remove this once all existing service targets have stopped
-    # setting |resources|. This target serves no purpose other than to ensure
-    # that |resources| is actually used, avoiding GN complaints.
-    source_set("${target_name}__unused_resources_target") {
-      testonly = true
-      sources = invoker.resources
-      deps = invoker.deps
-    }
-  }
-
   if (is_win) {
     executable_extension = "service.exe"
   } else {
     executable_extension = "service"
   }
 
-  executable(target_name) {
+  executable_target_name = base_target_name + "_executable"
+  executable_name = base_target_name + "." + executable_extension
+
+  executable(executable_target_name) {
     output_name = base_target_name
     output_extension = executable_extension
 
     if (defined(invoker.cflags)) {
       cflags = invoker.cflags
     }
     if (defined(invoker.cflags_c)) {
       cflags_c = invoker.cflags_c
     }
     if (defined(invoker.cflags_cc)) {
@@ skipping 53 matching lines @@
     if (defined(invoker.public)) {
       public = invoker.public
     }
     if (defined(invoker.sources)) {
       sources = invoker.sources
     }
     if (defined(invoker.testonly)) {
       testonly = invoker.testonly
     }
   }
+
+  copy(final_target_name) {
+    forward_variables_from(invoker,
+                           [
+                             "testonly",
+                             "visibility",
+                           ])
+    deps = [
+      ":${executable_target_name}",
+    ]
+
+    # NOTE: We have to explicitly inherit the same data_deps as the executable
+    # target itself, rather than specifying a data depenedency on the executable
+    # target. This avoids needless duplication of service binary artifacts in
+    # test isolates, as the executable is unused in its original location.
+    data_deps = service_data_deps
+
+    sources = [
+      "${root_out_dir}/${executable_name}",
+    ]
+    outputs = [
+      "${root_out_dir}/${packages_directory}/${base_target_name}/${executable_name}",
+    ]
+  }
 }