Add missing files in //device to appropriate BUILD.gn files.

device/generic_sensor/BUILD.gn

 # Copyright 2016 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")
 
 if (is_android) {
   import("//build/config/android/rules.gni")  # For generate_jni().
 }
 
 component("generic_sensor") {
   output_name = "generic_sensor"
   sources = [
     "generic_sensor_consts.h",
+    "generic_sensor_export.h",
     "linux/sensor_data_linux.cc",
     "linux/sensor_data_linux.h",
     "platform_sensor.cc",
     "platform_sensor.h",
     "platform_sensor_ambient_light_mac.cc",
     "platform_sensor_ambient_light_mac.h",
     "platform_sensor_android.cc",
     "platform_sensor_android.h",
     "platform_sensor_linux.cc",
     "platform_sensor_linux.h",
@@ skipping 95 matching lines @@
     "fake_platform_sensor_provider.cc",
     "fake_platform_sensor_provider.h",
   ]
 
   public_deps = [
     ":generic_sensor",
     "//base",
     "//testing/gmock",
   ]
 }