Build services as standalone executables

services/service_manager/public/cpp/service.gni

Index: services/service_manager/public/cpp/service.gni
diff --git a/services/service_manager/public/cpp/service.gni b/services/service_manager/public/cpp/service.gni
index 5faeb259bb86578856843f8ab23e5e1a11cd6324..2fb99919ab7bdf2a4f6765a11e642c61be28e014 100644
--- a/services/service_manager/public/cpp/service.gni
+++ b/services/service_manager/public/cpp/service.gni
@@ -11,12 +11,13 @@ if (is_android) {
 }
 
 # Generates a Service "package", which includes:
-# . A self-named subdirectory
-# . A binary .library
-# . A resources subdirectory alongside .library that contains the contents of
-#   "resources"
 #
-# The parameters of this template are those of a shared library.
+#   - 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)) {
@@ -25,12 +26,13 @@ template("service") {
 
   final_target_name = target_name
 
-  library_deps = []
+  service_deps = []
   if (defined(invoker.deps)) {
-    library_deps += invoker.deps
+    service_deps += invoker.deps
   }
 
-  library_data_deps = []
+  service_data_deps =
+      [ "//services/service_manager/public/cpp/standalone_service:main" ]
 
   if (defined(invoker.resources)) {
     copy_step_name = "${base_target_name}__copy_resources"
@@ -42,16 +44,22 @@ template("service") {
       if (defined(invoker.testonly)) {
         testonly = invoker.testonly
       }
-      deps = library_deps
+      deps = service_deps
     }
-    library_data_deps += [ ":$copy_step_name" ]
+    service_data_deps += [ ":$copy_step_name" ]
+  }
+
+  if (defined(invoker.data_deps)) {
+    service_data_deps += invoker.data_deps
   }
 
-  output = base_target_name + ".library"
-  library_target_name = base_target_name + "_library"
-  library_name = "${shlib_prefix}${library_target_name}${shlib_extension}"
+  executable_target_name = base_target_name + "_executable"
+  executable_name = base_target_name + ".service"
+
+  executable(executable_target_name) {
+    output_name = base_target_name
+    output_extension = "service"
 
-  shared_library(library_target_name) {
     if (defined(invoker.cflags)) {
       cflags = invoker.cflags
     }
@@ -83,22 +91,13 @@ template("service") {
       libs = invoker.libs
     }
 
-    data_deps = []
-    if (!defined(invoker.avoid_runner_cycle) || !invoker.avoid_runner_cycle) {
-      # Give the user an out; as some Services are depended on by the runner.
-      data_deps += [ "//services/service_manager/standalone" ]
-    }
-    if (defined(invoker.data_deps)) {
-      data_deps += invoker.data_deps
-    }
-    data_deps += library_data_deps
+    data_deps = service_data_deps
 
     deps = [
-      "//mojo/public/c/system:set_thunks_for_app",
-      "//services/service_manager/public/cpp:application_support",
+      "//services/service_manager/public/cpp/standalone_service:main",
     ]
 
-    deps += library_deps
+    deps += service_deps
     if (defined(invoker.public_deps)) {
       public_deps = invoker.public_deps
     }
@@ -138,14 +137,20 @@ template("service") {
                              "visibility",
                            ])
     deps = [
-      ":${library_target_name}",
+      ":${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 = [
-      "${root_shlib_dir}/${library_name}",
+      "${root_out_dir}/${executable_name}",
     ]
     outputs = [
-      "${root_out_dir}/${packages_directory}/${base_target_name}/${output}",
+      "${root_out_dir}/${packages_directory}/${base_target_name}/${executable_name}",
     ]
   }
 }