Add missing .h files to .gn files that have a .cc file next to it in the gn file already.

content/test/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/chrome_build.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
@@ skipping 910 matching lines @@
       "../browser/webrtc/webrtc_media_recorder_browsertest.cc",
       "../browser/webrtc/webrtc_webcam_browsertest.cc",
       "../browser/webrtc/webrtc_webcam_browsertest.h",
     ]
     deps += [ "//testing/perf" ]
   }
 
   if (enable_plugins) {
     sources += [
       "../renderer/pepper/fake_pepper_plugin_instance.cc",
+      "../renderer/pepper/fake_pepper_plugin_instance.h",
       "../renderer/pepper/mock_renderer_ppapi_host.cc",
+      "../renderer/pepper/mock_renderer_ppapi_host.h",
       "../renderer/pepper/pepper_device_enumeration_host_helper_unittest.cc",
       "../renderer/pepper/pepper_file_chooser_host_unittest.cc",
       "../renderer/pepper/pepper_graphics_2d_host_unittest.cc",
       "../renderer/pepper/pepper_url_request_unittest.cc",
       "../renderer/pepper/pepper_webplugin_impl_browsertest.cc",
       "../renderer/pepper/plugin_power_saver_helper_browsertest.cc",
       "../test/ppapi/ppapi_browsertest.cc",
       "../test/ppapi/ppapi_test.cc",
       "../test/ppapi/ppapi_test.h",
     ]
@@ skipping 670 matching lines @@
       "../renderer/media/media_stream_constraints_util_sets_unittest.cc",
       "../renderer/media/media_stream_constraints_util_unittest.cc",
       "../renderer/media/media_stream_constraints_util_video_content_unittest.cc",
       "../renderer/media/media_stream_constraints_util_video_device_unittest.cc",
       "../renderer/media/media_stream_dispatcher_unittest.cc",
       "../renderer/media/media_stream_video_capturer_source_unittest.cc",
       "../renderer/media/media_stream_video_renderer_sink_unittest.cc",
       "../renderer/media/media_stream_video_source_unittest.cc",
       "../renderer/media/media_stream_video_track_unittest.cc",
       "../renderer/media/mock_constraint_factory.cc",
+      "../renderer/media/mock_constraint_factory.h",
       "../renderer/media/mock_media_stream_registry.cc",
       "../renderer/media/mock_media_stream_registry.h",
       "../renderer/media/mock_media_stream_video_sink.cc",
       "../renderer/media/mock_media_stream_video_sink.h",
       "../renderer/media/mock_media_stream_video_source.cc",
       "../renderer/media/mock_media_stream_video_source.h",
       "../renderer/media/peer_connection_tracker_unittest.cc",
       "../renderer/media/rtc_data_channel_handler_unittest.cc",
       "../renderer/media/rtc_peer_connection_handler_unittest.cc",
       "../renderer/media/speech_recognition_audio_sink_unittest.cc",
@@ skipping 226 matching lines @@
   if (is_android) {
     deps += [ "//testing/android/native_test:native_test_native_code" ]
   }
 }
 
 group("fuzzers") {
   deps = [
     "//content/test/fuzzer",
   ]
 }