Adds the Material Text Accessibility library to the iOS build.

ios/third_party/material_text_accessibility_ios/BUILD.gn

Index: ios/third_party/material_text_accessibility_ios/BUILD.gn
diff --git a/ios/third_party/material_text_accessibility_ios/BUILD.gn b/ios/third_party/material_text_accessibility_ios/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..573f526f26b012cdd29003fab870bbe34d8824cc
--- /dev/null
+++ b/ios/third_party/material_text_accessibility_ios/BUILD.gn
@@ -0,0 +1,25 @@
+# Copyright 2016 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.
+
+config("material_text_accessibility_ios_config") {
+  include_dirs = [ "src/src" ]
+  visibility = [ ":material_text_accessibility_ios" ]
+}
+
+source_set("material_text_accessibility_ios") {
+  sources = [
+    "src/src/MDFTextAccessibility-Bridging-Header.h",
+    "src/src/MDFTextAccessibility.h",
+    "src/src/MDFTextAccessibility.m",
+    "src/src/private/MDFColorCalculations.h",
+    "src/src/private/MDFColorCalculations.m",
+    "src/src/private/MDFImageCalculations.h",
+    "src/src/private/MDFImageCalculations.m",
+    "src/src/private/NSArray+MDFUtils.h",
+    "src/src/private/NSArray+MDFUtils.m",
+  ]
+
+  public_configs = [ ":material_text_accessibility_ios_config" ]
+  configs += [ ":material_text_accessibility_ios_config" ]
+}