Don't compile code for desktop zoom or GuestViews on mobile platforms.

content/browser/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("//gpu/vulkan/features.gni")
 import("//media/media_options.gni")
 import("//ppapi/features/features.gni")
 import("//printing/features/features.gni")
@@ skipping 751 matching lines @@
     "histogram_controller.h",
     "histogram_internals_request_job.cc",
     "histogram_internals_request_job.h",
     "histogram_internals_url_loader.cc",
     "histogram_internals_url_loader.h",
     "histogram_message_filter.cc",
     "histogram_message_filter.h",
     "histogram_subscriber.h",
     "histogram_synchronizer.cc",
     "histogram_synchronizer.h",
-    "host_zoom_level_context.cc",
-    "host_zoom_level_context.h",
-    "host_zoom_map_impl.cc",
-    "host_zoom_map_impl.h",
-    "host_zoom_map_observer.cc",
-    "host_zoom_map_observer.h",
     "image_capture/image_capture_impl.cc",
     "image_capture/image_capture_impl.h",
     "indexed_db/cursor_impl.cc",
     "indexed_db/cursor_impl.h",
     "indexed_db/database_impl.cc",
     "indexed_db/database_impl.h",
     "indexed_db/indexed_db.h",
     "indexed_db/indexed_db_active_blob_registry.cc",
     "indexed_db/indexed_db_active_blob_registry.h",
     "indexed_db/indexed_db_backing_store.cc",
@@ skipping 1161 matching lines @@
       "APPCACHE_USE_SIMPLE_CACHE",
       "ENABLE_SCREEN_CAPTURE=1",
     ]
     libs += [ "jnigraphics" ]
   } else {
     # Not Android.
     sources += [
       # Devtools frontend not included in Android
       "devtools/devtools_frontend_host_impl.cc",
       "devtools/devtools_frontend_host_impl.h",
+      "host_zoom_level_context.cc",
+      "host_zoom_level_context.h",
+      "host_zoom_map_impl.cc",
+      "host_zoom_map_impl.h",
+      "host_zoom_map_observer.cc",
+      "host_zoom_map_observer.h",
 
       # Most speech code is non-Android.
       "speech/audio_buffer.cc",
       "speech/audio_buffer.h",
       "speech/audio_encoder.cc",
       "speech/audio_encoder.h",
       "speech/chunked_byte_buffer.cc",
       "speech/chunked_byte_buffer.h",
       "speech/endpointer/endpointer.cc",
       "speech/endpointer/endpointer.h",
@@ skipping 168 matching lines @@
   if (!is_component_build) {
     public_deps = [
       ":browser",
     ]
   } else {
     public_deps = [
       "//third_party/leveldatabase",
     ]
   }
 }