GN + Android: extract android_standalone_library rule.

build/config/android/internal_rules.gni

Index: build/config/android/internal_rules.gni
diff --git a/build/config/android/internal_rules.gni b/build/config/android/internal_rules.gni
index ce6e4281883753a475433042f1727a28f64afdac..37727692965b6eb46ec368d23ab3bd5223129ca7 100644
--- a/build/config/android/internal_rules.gni
+++ b/build/config/android/internal_rules.gni
@@ -66,12 +66,13 @@ template("dex") {
     testonly = invoker.testonly
   }
 
-  assert(defined(invoker.sources))
   assert(defined(invoker.output))
   action(target_name) {
     script = "//build/android/gyp/dex.py"
     depfile = "$target_gen_dir/$target_name.d"
-    sources = invoker.sources
+    if (defined(invoker.sources)) {
+      sources = invoker.sources
+    }
     outputs = [
       depfile,
       invoker.output,
@@ -103,7 +104,9 @@ template("dex") {
       args += invoker.args
     }
 
-    args += rebase_path(invoker.sources, root_build_dir)
+    if (defined(invoker.sources)) {
+      args += rebase_path(invoker.sources, root_build_dir)
+    }
   }
 }
 
@@ -163,7 +166,7 @@ template("write_build_config") {
   build_config = invoker.build_config
 
   assert(type == "android_apk" || type == "java_library" ||
-         type == "android_resources")
+         type == "android_resources" || type == "deps_dex")
 
   action(target_name) {
     script = "//build/android/gyp/write_build_config.py"
@@ -201,11 +204,12 @@ template("write_build_config") {
     is_java_library = type == "java_library"
     is_apk = type == "android_apk"
     is_android_resources = type == "android_resources"
+    is_deps_dex = type == "deps_dex"
 
-    supports_android = is_apk || is_android_resources ||
+    supports_android = is_apk || is_android_resources || is_deps_dex ||
                        (is_java_library && defined(invoker.supports_android) &&
                         invoker.supports_android)
-    requires_android = is_apk || is_android_resources ||
+    requires_android = is_apk || is_android_resources || is_deps_dex ||
                        (is_java_library && defined(invoker.requires_android) &&
                         invoker.requires_android)
 
@@ -216,6 +220,7 @@ template("write_build_config") {
     assert(is_java_library || true)
     assert(is_apk || true)
     assert(is_android_resources || true)
+    assert(is_deps_dex || true)
 
     if (is_java_library || is_apk) {
       args += [
@@ -224,7 +229,7 @@ template("write_build_config") {
       ]
     }
 
-    if (is_apk || (is_java_library && supports_android)) {
+    if (is_apk || is_deps_dex || (is_java_library && supports_android)) {
       args += [
         "--dex-path",
         rebase_path(invoker.dex_path, root_build_dir),
@@ -898,22 +903,6 @@ template("java_library_impl") {
       ]
       output = _dex_path
     }
-
-    if (defined(invoker.standalone_dex_path)) {
-      _final_deps += [ ":${_template_name}__standalone_dex" ]
-      _rebased_build_config = rebase_path(_build_config, root_build_dir)
-      dex("${_template_name}__standalone_dex") {
-        sources = [
-          _jar_path,
-        ]
-        inputs = [
-          _build_config,
-        ]
-        output = invoker.standalone_dex_path
-        dex_arg_key = "${_rebased_build_config}:final_dex:dependency_dex_files"
-        args = [ "--inputs=@FileArg($dex_arg_key)" ]
-      }
-    }
   }
 
   group(target_name) {
@@ -1061,3 +1050,25 @@ template("copy_ex") {
     }
   }
 }
+
+# Produces a single .dex.jar out of a set of Java dependencies.
+template("deps_dex") {
+  build_config = "$target_gen_dir/${target_name}.build_config"
+  write_build_config("${target_name}__build_config") {
+    type = "deps_dex"
+    deps = invoker.deps
+
+    build_config = build_config
+    dex_path = invoker.dex_path
+  }
+
+  rebased_build_config = rebase_path(build_config, root_build_dir)
+  dex(target_name) {
+    inputs = [
+      build_config,
+    ]
+    output = invoker.dex_path
+    dex_arg_key = "${rebased_build_config}:final_dex:dependency_dex_files"
+    args = [ "--inputs=@FileArg($dex_arg_key)" ]
+  }
+}