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

content/shell/android/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/android/config.gni")
 import("//build/config/android/rules.gni")
 import("//third_party/icu/config.gni")
 
 generate_jni("content_shell_jni_headers") {
   jni_package = "content/shell"
@@ skipping 218 matching lines @@
       ":$_linker_test_apk_target_name",
       ":$_linker_test_apk_test_runner_target_name",
     ]
   }
 
   shared_library("linker_test") {
     testonly = true
     sources = [
       "linker_test_apk/chromium_linker_test_android.cc",
       "linker_test_apk/chromium_linker_test_linker_tests.cc",
+      "linker_test_apk/chromium_linker_test_linker_tests.h",
     ]
 
     deps = [
       ":linker_test_jni_headers",
       "//build/config/sanitizers:deps",
       "//content/shell:content_shell_lib",
 
       # Required to include "content/public/browser/android/compositor.h"
       # in chromium_linker_test_android.cc :-(
       "//skia",
@@ skipping 14 matching lines @@
   testonly = true
   deps = [
     ":content_shell_java",
     "//base:base_java",
     "//content/public/android:content_java",
     "//testing/android/native_test:native_test_java",
     "//ui/android:ui_java",
   ]
   java_files = [ "browsertests/src/org/chromium/content_shell/browsertests/ContentShellBrowserTestActivity.java" ]
 }