Add a DiscardableMemoryShmemeAllocator.

mojo/services/html_viewer/BUILD.gn

 # Copyright 2014 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("//testing/test.gni")
 import("//third_party/mojo/src/mojo/public/mojo.gni")
 import("//third_party/mojo/src/mojo/public/mojo_application.gni")
 
 action("generate_blink_resource_map") {
   script = "//mojo/services/html_viewer/generate_blink_resource_map.py"
@@ skipping 22 matching lines @@
     "ax_provider_impl.h",
     "blink_basic_type_converters.cc",
     "blink_basic_type_converters.h",
     "blink_input_events_type_converters.cc",
     "blink_input_events_type_converters.h",
     "blink_platform_impl.cc",
     "blink_platform_impl.h",
     "blink_resource_constants.h",
     "blink_url_request_type_converters.cc",
     "blink_url_request_type_converters.h",
+    "discardable_memory_allocator.cc",
+    "discardable_memory_allocator.h",
     "html_document.cc",
     "html_document.h",
     "mojo_blink_platform_impl.cc",
     "mojo_blink_platform_impl.h",
     "webclipboard_impl.cc",
     "webclipboard_impl.h",
     "webcookiejar_impl.cc",
     "webcookiejar_impl.h",
     "weblayertreeview_impl.cc",
     "weblayertreeview_impl.h",
@@ skipping 116 matching lines @@
     deps = [
       ":lib",
     ]
   }
 }
 
 test("tests") {
   output_name = "html_viewer_unittests"
   sources = [
     "ax_provider_impl_unittest.cc",
+    "discardable_memory_allocator_unittest.cc",
   ]
   deps = [
     ":lib",
     "//base/test:run_all_unittests",
   ]
 }