[iOS][GN] Port ios_web_unittests to build with gn

ios/web/js_compile.gni

+# Copyright 2015 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.
+
+closure_compiler_wrapper = "closure_compiler.py"
+closure_compiler_path = "//third_party/closure_compiler/compiler/compiler.jar"
+
+# Defines a target that create a JavaScript bundle using the closure compiler.
+#
+# Variables
+#   sources:
+#     List of JavaScript files to compile into the bundle.
+#
+#   closure_entry_point:
+#     Name of the entry point closure module.
+#
+#   deps (optional)
+#     List of targets required by this target.
+#
+#   visibility (optional)
+#     Visibility restrictions.
+#
+# Generates a single JavaScript bundle file that can be put in the application
+# bundle.
+#
+# TODO(eugenebut): this should uses the same error flags as js_compile_checked.
+template("js_compile_bundle") {
+  assert(defined(invoker.sources),
+         "Need sources in $target_name listing the js files.")
+
+  assert(defined(invoker.closure_entry_point),
+         "Need closure_entry_point in $target_name for generated js file.")
+
+  action(target_name) {
+    forward_variables_from(invoker,
+                           [
+                             "deps",
+                             "visibility",
+                           ])
+
+    script = closure_compiler_wrapper
+    inputs = [
+      closure_compiler_path,
+    ]
+
+    outputs = [
+      "$target_gen_dir/$target_name.js",
+    ]
+    sources = invoker.sources
+
+    args = [
+             rebase_path(closure_compiler_path, root_build_dir),
+             "--compilation_level",
+             "SIMPLE_OPTIMIZATIONS",
+             "--js",
+           ] + rebase_path(sources, root_build_dir) + [ "--js_output_file" ] +
+           rebase_path(outputs, root_build_dir) +
+           [
+             "--only_closure_dependencies",
+             "--closure_entry_point",
+             invoker.closure_entry_point,
+           ]
+
+    # TODO(sdefresne): add the generated bundle to the list of files to move
+    # in the application bundle, equivalent to the following gyp code:
+    #
+    # "link_settings": {
+    #   "mac_bundle_resources": [
+    #     "<(SHARED_INTERMEDIATE_DIR)/<(RULE_INPUT_NAME).js",
+    #   ],
+    # },
+  }
+}
+
+# Defines a target that compile JavaScript files with error checking using the
+# closure compiler.
+#
+# Variables
+#   sources:
+#     List of JavaScript files to compile.
+#
+#   compile (optional, defaults to true)
+#     If false or undefined, the JavaScript files will not be compiled but

[Eugene But (OOO till 7-30), 2015/10/08 16:10:41]

I don't think that this comment is accurate. if invoker.compile, then source
code will be compiled (unless I misunderstood gn rules)

[Dirk Pranke, 2015/10/08 17:49:45]

Why even have the 'copy' part of this template? Why not just have a separate
copy target for that case?

[sdefresne, 2015/10/09 13:54:45]

Removed the comment as I've changed the value to a global configurable by the
user.
My plan was to stay as close as the gyp rule as possible. The caller could just
pass the value of a global (as is done with gyp) and do not have to care how to
implement the "compile" flag (there's only one caller currently, so not really
necessary, but if/when we add more, it will be good to be able to have a central
place responsible for this flag instead of multiple location).

+#     just copied to the destination.
+#
+#   deps (optional)
+#     List of targets required by this target.
+#
+#   visibility (optional)
+#     Visibility restrictions.
+#
+# TODO(eugenebut): use flags from third_party/closure_compiler/closure_args.gni
+# once they are the same.
+template("js_compile_checked") {
+  assert(defined(invoker.sources),
+         "Need sources in $target_name listing the js files.")
+
+  if (defined(invoker.compile)) {
+    compile = invoker.compile
+  } else {
+    compile = true
+  }
+
+  if (compile) {
+    action_foreach(target_name) {
+      forward_variables_from(invoker,
+                             [
+                               "deps",
+                               "visibility",
+                             ])
+
+      script = closure_compiler_wrapper
+      inputs = [
+        closure_compiler_path,
+      ]
+
+      sources = invoker.sources
+
+      outputs = [
+        "$target_gen_dir/{{source_file_part}}",
+      ]
+
+      # TODO(eugenebut): need to enable the following compilation checks once
+      # the corresponding errors have been fixed:
+      #   --jscomp_error=checkTypes
+      #   --jscomp_error=checkVars
+      #   --jscomp_error=missingProperties
+      #   --jscomp_error=missingReturn
+      #   --jscomp_error=undefinedVars
+
+      args = [
+        rebase_path(closure_compiler_path, root_build_dir),
+        "--compilation_level",
+        "SIMPLE_OPTIMIZATIONS",
+        "--jscomp_error=accessControls",
+        "--jscomp_error=ambiguousFunctionDecl",
+        "--jscomp_error=constantProperty",
+        "--jscomp_error=deprecated",
+        "--jscomp_error=externsValidation",
+        "--jscomp_error=globalThis",
+        "--jscomp_error=invalidCasts",
+        "--jscomp_error=nonStandardJsDocs",
+        "--jscomp_error=suspiciousCode",
+        "--jscomp_error=undefinedNames",
+        "--jscomp_error=unknownDefines",
+        "--jscomp_error=uselessCode",
+        "--jscomp_error=visibility",
+        "--js",
+        "{{source}}",
+        "--js_output_file",
+        rebase_path("$target_gen_dir/{{source_file_part}}", root_build_dir),
+      ]
+
+      # TODO(sdefresne): add the generated bundle to the list of files to move
+      # in the application bundle, equivalent to the following gyp code:
+      #
+      # "link_settings": {
+      #   "mac_bundle_resources": [
+      #     "<(SHARED_INTERMEDIATE_DIR)/<(RULE_INPUT_NAME).js",
+      #   ],
+      # },
+    }
+  } else {
+    copy(target_name) {
+      forward_variables_from(invoker,
+                             [
+                               "deps",
+                               "visibility",
+                             ])
+
+      sources = invoker.sources
+      outputs = [
+        "$target_gen_dir/{{source_file_part}}",
+      ]
+
+      # TODO(sdefresne): add the generated bundle to the list of files to move
+      # in the application bundle, equivalent to the following gyp code:
+      #
+      # "link_settings": {
+      #   "mac_bundle_resources": [
+      #     "<(SHARED_INTERMEDIATE_DIR)/<(RULE_INPUT_NAME).js",
+      #   ],
+      # },
+    }
+  }
+}