gn: Address some TODO(GYP)s in the toplevel BUILD.gn

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index f9c6907362d928823d7e44ed3f7ff07361d57c49..4f47a899b8f2125c6b08409a507ef09f70601e0e 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -38,19 +38,11 @@ if (is_official_build) {
   assert(!is_component_build)
 }
 
-# This file defines the following five main targets:
-#
-# "both_gn_and_gyp" should list every root target (target that nothing else

[Nico, 2017/04/25 20:45:42]

This target no longer exists.

-# depends on) built by GN that is also built in the GYP build.
+# This file defines the following three main targets:
 #
 # "gn_all" should (transitively) cause everything to be built; if you run
 # 'ninja gn_all' and then 'ninja all', the second build should do no work.
 #
-# "gn_only" should list every root target that is *not* intended to be built in

[Nico, 2017/04/25 20:45:42]

Neither does this.

-# a GYP build. Because GN has different rules for deciding what an 'all' build
-# is, this may end up including targets that are actually defined in a GYP
-# build but not dependencies of GYP's "all" (and so not actually built).
-#
 # "gn_visibility": targets that are normally not visible to top-level targets,
 # but are built anyway by "all". Since we don't want any such targets, we have
 # this placeholder to make sure hidden targets that aren't otherwise depended
@@ -63,8 +55,8 @@ if (is_official_build) {
 # wildcards.
 #
 # Lastly, none of these targets are guaranteed to be the same as what ninja
-# will build with "all". For more on how "all" works and the differences in how
-# GYP and GN determine "all", see crbug.com/503241.
+# will build with "all". For more on how "all" works and how GN determines
+# "all", see crbug.com/503241.
 #
 # TODO(GYP_GONE): crbug.com/481694. Make sure that the above is true and there
 # are scripts run on the bots that enforce this. Once the GYP migration is
@@ -155,8 +147,6 @@ group("gn_all") {
   }
 
   if (!is_ios) {
-    # TODO(GYP): Figure out which of these should actually build on iOS,
-    # and whether there should be other targets that are iOS-only and missing.

[Nico, 2017/04/25 20:45:42]

This list of non-iOS targets looks roughly correct to me, so I declare this as
done.

     deps += [
       "//cc:cc_unittests",
       "//chrome/test:telemetry_perf_unittests",
@@ -545,10 +535,6 @@ group("gn_all") {
       "//third_party/tcmalloc:addr2line-pdb",
       "//tools/win/chromeexts:chromeexts",
     ]
-    deps -= [
-      "//crypto:crypto_unittests",  # TODO(GYP)
-      "//net:net_unittests",  # TODO(GYP)

[Nico, 2017/04/25 20:45:42]

They both build fine on Windows.

-    ]
 
     if (!(is_component_build && is_debug && target_cpu == "x86")) {
       deps +=
@@ -621,7 +607,6 @@ group("gn_all") {
     # TODO(GYP): Figure out if any of these should be in gn_all
     # and figure out how cross-platform they are
     deps += [
-      ":gn_mojo_targets",
       "//chrome/installer/util:strings",
       "//chrome/tools/convert_dict",
       "//components/constrained_window:unit_tests",
@@ -824,19 +809,6 @@ if (is_chromeos) {
   }
 }
 
-group("gn_mojo_targets") {
-  testonly = true
-  if (is_linux && !is_chromeos) {
-    # TODO(GYP): Figure out if any of these should be in gn_all
-    # and figure out how cross-platform they are
-    deps = [
-      "//ipc:ipc_tests",
-      "//mojo:tests",
-      "//services:service_unittests",

[Nico, 2017/04/25 20:45:42]

All these are depended on without this target already.

-    ]
-  }
-}
-
 group("gn_visibility") {
   deps = [
     "//build/config/sanitizers:options_sources",