Rewrite implementation of ClipboardRecentContent in Objective C.

components/open_from_clipboard/BUILD.gn

 # Copyright 2015 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.
 
 static_library("open_from_clipboard") {
   sources = [
     "clipboard_recent_content.cc",
     "clipboard_recent_content.h",
     "clipboard_recent_content_ios.h",
     "clipboard_recent_content_ios.mm",
   ]
 
   deps = [
+    ":open_from_clipboard_impl",
     "//base",
+    "//net",
     "//url",
   ]
 }
 
+# Helper classes used by "open_from_clipboard" target. These classes have
+# no dependencies on "//base:i18n".
+source_set("open_from_clipboard_impl") {
+  sources = [
+    "clipboard_recent_content_impl_ios.h",
+    "clipboard_recent_content_impl_ios.mm",
+  ]
+  deps = [
+    "//base",
+  ]
+  assert_no_deps = [ "//base:i18n" ]
+  if (is_ios) {
+    configs += [ "//build/config/compiler:enable_arc" ]
+  }
+}
+
 static_library("test_support") {
   testonly = true
   sources = [
     "fake_clipboard_recent_content.cc",
     "fake_clipboard_recent_content.h",
   ]
 
   deps = [
     ":open_from_clipboard",
     "//base",
     "//url",
   ]
 }
 
 source_set("unit_tests") {
   testonly = true
   sources = [
     "clipboard_recent_content_ios_unittest.mm",
   ]
 
   deps = [
     ":open_from_clipboard",
     "//base",
     "//testing/gtest",
   ]
 }