patch from chinmaygarde@ to make progress on mac, ios.

BUILD.gn

 # Copyright (c) 2013 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.
 
 # This is the root build file for GN. GN will start processing by loading this
 # file, and recursively load all dependencies until all dependencies are either
 # resolved or known not to exist (which will cause the build to fail). So if
 # you add a new build file, there must be some path of dependencies from this
 # file to your new one or GN won't know about it.
 
@@ skipping 47 matching lines @@
 
 # The "both_gn_and_gyp" target should reflect every target that is built
 # in both the GN and GYP builds, and ideally it should match the
 # "both_gn_and_gyp" target in build/gn_migration.gypi line-for-line.
 #
 # TODO(GYP): Add build steps that check and enforce this on the bots.
 group("both_gn_and_gyp") {
   testonly = true
   deps = [
     "//base:base_unittests",
-    "//sync:sync_unit_tests",
   ]
+
   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.
     deps += [
       "//cc:cc_unittests",
       "//chrome",
       "//chrome/test:browser_tests",
       "//chrome/test:interactive_ui_tests",
       "//chrome/test:sync_integration_tests",
       "//chrome/test:unit_tests",
       "//chrome/test/chromedriver:chromedriver_unittests",
       "//components:components_browsertests",
       "//components:components_unittests",
@@ skipping 46 matching lines @@
       "//ppapi/examples/stub",
       "//ppapi/examples/threading",
       "//ppapi/examples/url_loader",
       "//ppapi/examples/video_capture",
       "//ppapi/examples/video_decode",
       "//ppapi/examples/video_effects",
       "//ppapi/examples/video_encode",
       "//printing:printing_unittests",
       "//skia:skia_unittests",
       "//sql:sql_unittests",
+      "//sync:sync_unit_tests",
       "//third_party/WebKit/Source/platform:heap_unittests",
       "//third_party/WebKit/Source/platform:platform_unittests",
       "//third_party/WebKit/Source/web:webkit_unit_tests",
       "//third_party/WebKit/Source/wtf:wtf_unittests",
       "//third_party/cacheinvalidation:cacheinvalidation_unittests",
       "//third_party/codesighs",
       "//third_party/mojo/src/mojo/edk/system:mojo_system_unittests",
       "//third_party/mojo/src/mojo/edk/test:mojo_public_bindings_unittests",
       "//third_party/mojo/src/mojo/edk/test:mojo_public_environment_unittests",
       "//third_party/mojo/src/mojo/edk/test:mojo_public_system_unittests",
@@ skipping 445 matching lines @@
   }
 
   if (!is_ios) {
     deps += [ "//gpu/skia_runner:skia_runner" ]
   }
 }
 
 group("gn_only") {
   testonly = true
 
+  deps = []
+
   if (!is_ios) {
-    deps = [
-      "//mandoline:all",
-    ]
+    deps += [ "//mandoline:all" ]
   }
 
   if (!is_android && !is_ios) {
     deps += [ "//components/proximity_auth:proximity_auth_unittests" ]
   }
 
   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 += [
@@ skipping 314 matching lines @@
       "//ui/views:views_unittests",  # TooltipControllerTest failures
       "//ui/wm:wm_unittests",  # PASSES 4/21/2015
       "//url:url_unittests",  # PASSES 4/17/2015
 
       # TODO(GYP) nacl_integration
       # TODO(GYP) telemetry_perf_unittests
       # TODO(GYP) telemetry_unittests
     ]
   }
 }