Add ios_web_view_shell_egtests target and accessibility labels to shell.

ios/web_view/shell/test/BUILD.gn

+# 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.
+
+import("//ios/build/config.gni")
+import("//ios/third_party/earl_grey/ios_eg_test.gni")
+
+group("all_tests") {
+  testonly = true
+  deps = [
+    ":ios_web_view_shell_egtests",
+  ]
+}
+
+ios_eg_test("ios_web_view_shell_egtests") {
+  info_plist = "//ios/web_view/shell/Info.plist"
+  sources = [
+    "shell_egtest.mm",
+  ]
+
+  deps = [
+    ":earl_grey_test_support",
+
+    # All shared libraries must have the sanitizer deps to properly link in
+    # asan mode (this target will be empty in other cases).
+    "//build/config/sanitizers:deps",
+  ]
+
+  configs += [ "//build/config/compiler:enable_arc" ]
+
+  assert_no_deps = ios_assert_no_deps
+}
+
+source_set("earl_grey_test_support") {
+  testonly = true
+
+  deps = [
+    "//base",
+    "//ios/testing:ios_test_support",
+    "//ios/third_party/earl_grey",
+    "//ios/web_view/shell",
+  ]
+
+  public_deps = [
+    "//build/config/ios:xctest",
+  ]
+
+  sources = [
+    "earl_grey/shell_matchers.h",
+    "earl_grey/shell_matchers.mm",
+  ]
+
+  configs += [ "//build/config/compiler:enable_arc" ]
+}