Fixing a crash in MediaCustomControlsFullscreenDetector when the page is destroyed

third_party/WebKit/Source/platform/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("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//testing/libfuzzer/fuzzer_test.gni")
 import("//testing/test.gni")
 import("//third_party/WebKit/public/public_features.gni")
 import("//third_party/WebKit/Source/build/scripts/scripts.gni")
@@ skipping 1551 matching lines @@
     "scheduler/child/scheduler_tqm_delegate_for_test.cc",
     "scheduler/test/fake_renderer_scheduler.cc",
     "scheduler/test/fake_web_task_runner.cc",
     "scheduler/test/fake_web_task_runner.h",
     "scheduler/test/lazy_scheduler_message_loop_delegate_for_tests.cc",
     "scheduler/test/lazy_scheduler_message_loop_delegate_for_tests.h",
     "scheduler/test/renderer_scheduler_test_support.cc",
     "scroll/ScrollbarTestSuite.h",
     "testing/CompositorTest.cpp",
     "testing/CompositorTest.h",
+    "testing/EmptyWebMediaPlayer.cpp",
+    "testing/EmptyWebMediaPlayer.h",
     "testing/FakeDisplayItemClient.h",
     "testing/FakeGraphicsLayer.h",
     "testing/FakeGraphicsLayerClient.h",
     "testing/FontTestHelpers.cpp",
     "testing/FontTestHelpers.h",
     "testing/FuzzedDataProvider.cpp",
     "testing/FuzzedDataProvider.h",
     "testing/GeometryPrinters.cpp",
     "testing/GeometryPrinters.h",
     "testing/HistogramTester.cpp",
@@ skipping 480 matching lines @@
     "//third_party/WebKit/Source:config",
     "//third_party/WebKit/Source:inside_blink",
   ]
 
   deps = [
     ":test_support",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }