Stop disabling force_compositing_mode for background RenderViews.

content/content_renderer.gypi

 # Copyright (c) 2012 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.
 
 {
   'dependencies': [
     'content_common_mojo_bindings',
     '../gin/gin.gyp:gin',
     '../jingle/jingle.gyp:jingle_glue',
     '../media/media.gyp:media',
@@ skipping 140 matching lines @@
     'renderer/gpu/compositor_output_surface.cc',
     'renderer/gpu/compositor_output_surface.h',
     'renderer/gpu/compositor_software_output_device.cc',
     'renderer/gpu/compositor_software_output_device.h',
     'renderer/gpu/delegated_compositor_output_surface.cc',
     'renderer/gpu/delegated_compositor_output_surface.h',
     'renderer/gpu/gpu_benchmarking_extension.cc',
     'renderer/gpu/gpu_benchmarking_extension.h',
     'renderer/gpu/mailbox_output_surface.cc',
     'renderer/gpu/mailbox_output_surface.h',
+    'renderer/gpu/null_output_surface.h',
     'renderer/gpu/render_widget_compositor.cc',
     'renderer/gpu/render_widget_compositor.h',
     'renderer/gpu/stream_texture_host_android.cc',
     'renderer/gpu/stream_texture_host_android.h',
     'renderer/idle_user_detector.cc',
     'renderer/idle_user_detector.h',
     'renderer/image_loading_helper.cc',
     'renderer/image_loading_helper.h',
     'renderer/ime_event_guard.cc',
     'renderer/ime_event_guard.h',
@@ skipping 610 matching lines @@
     }],
   ],
   'target_conditions': [
     ['OS=="android"', {
       'sources/': [
         ['include', '^renderer/render_view_linux\\.cc$'],
       ],
     }],
   ],
 }