[remoting android] Make Android credits a GN template.

remoting/android/credits_tmpl.gni

+# Copyright 2017 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.
+
+# Generate Android credits HTML file, based on the third-party dependencies of
+# a provided GN target.
+# Parameters:
+#   gn_target: The target whose dependencies should be listed in the credits.
+template("remoting_android_credits") {
+  action(target_name) {
+    _credits_html_file = "$target_gen_dir/credits.html"

[agrieve, 2017/03/21 02:07:13]

unintuitively, $target_gen_dir == "gen/remoting/android", so what you have here
would cause errors if two remoting_android_credits() existed in the same
BUILD.gn file.

Instead, do: 
_credits_html_file = "$target_gen_dir/$target_name/credits.html"

or:
_credits_html_file = "$target_gen_dir/$target_name-credits.html"

[Lambros, 2017/03/22 21:31:00]

Done.

+    _credits_template = "//remoting/credits/credits.tmpl"
+    _credits_entry_template = "//remoting/credits/credits_entry.tmpl"
+    script = "//tools/licenses.py"
+    depfile = "$target_gen_dir/$target_name.d"
+    inputs = [
+      _credits_template,
+      _credits_entry_template,
+    ]
+    outputs = [
+      _credits_html_file,
+    ]
+    args = [
+      "credits",
+      rebase_path(_credits_html_file, root_build_dir),
+      "--file-template",
+      rebase_path(_credits_template, root_build_dir),
+      "--entry-template",
+      rebase_path(_credits_entry_template, root_build_dir),
+      "--depfile",
+      rebase_path(depfile, root_build_dir),
+      "--gn-target",
+      invoker.gn_target,
+      "--gn-out-dir",
+      rebase_path(root_build_dir),
+    ]
+  }
+
+  # Copies the generated HTML and the source CSS/JS, into a new directory for
+  # Android resource processing.
+  # The target is named this way, instead of "..._raw_resources", specifically
+  # to avoid matching any of the _java_target_whitelist items in
+  # build/config/android/internal_rules.gni
+  copy(target_name + "_resources_raw") {
+    _copy_target_name = target_name + "_resources_raw"

[agrieve, 2017/03/21 02:07:13]

I think this will evaluate to "credits_resources_raw_resources_raw".

target_name changes within the scope of the copy target to be the copy target's
name.

[Lambros, 2017/03/22 21:31:00]

In my testing, this doesn't seem to be the case. target_name retains the
original name of the template instance, even inside a target scope inside the
template.

+    sources = [
+                "//remoting/credits/credits_css.css",
+                "//remoting/credits/credits_js.js",
+              ] + get_target_outputs(":$target_name")

[agrieve, 2017/03/21 02:07:13]

Might likewise be an issue here.

[Lambros, 2017/03/22 21:31:00]

Same here.

+    outputs = [
+      "$target_gen_dir/${_copy_target_name}/res/raw/{{source_file_part}}",
+    ]
+    deps = [
+      ":$target_name",
+    ]
+  }
+}