Add the "is_ensemble" build variable.

media/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/arm.gni")
 import("//build/config/features.gni")
 import("//build/config/linux/pkg_config.gni")
 import("//build/config/ui.gni")
 import("//media/media_options.gni")
@@ skipping 470 matching lines @@
     "//crypto:platform",  # TODO(ajwong): This used to be provided by crypto.gyp via export_dependent_settings
     "//gpu/command_buffer/common",
     "//skia",
     "//third_party/libyuv",
     "//third_party/opus",
     "//ui/events:events_base",
     "//ui/gfx",
     "//ui/gfx/geometry",
     "//url",
   ]
+
+  if (is_ensemble) {

[DaleCurtis, 2015/02/11 21:58:01]

I think it'll be less error prone if you gate the inclusion of these files and
deps on !is_ensemble instead; that way we only have one file listing for each
too.

[wtc, 2015/02/11 23:40:47]

Originally I did it this way to minimize my changes to media/BUILD.gn. Also I
felt that the reason we need to exclude these source files for the is_ensemble
case seems rather add-hoc, so I didn't want to muck with the main source file
and deps lists.

I just looked up this issue in the GN Style Guide. The Style Guide recommends
the current approach as the default:

  * Generally include all sources at the top and remove sources if they do
    not apply in a particular case. If you have a bunch of files for a
    particular case, you can consider adding them in that case to avoid
    listing them twice if it seems more clear.

The current approach also allows another special build configuration to remove
some of these source files and deps independently.

Did this convince you? Or would you still like me to gate the inclusion of these
source files and deps on !in_ensemble instead?

[DaleCurtis, 2015/02/11 23:53:46]

I dislike the double listing and much prefer to optionally add them if it can be
done without a bunch of !is_ensemble sections (which it seems like it can).

+    # Remove source files and dependencies that need X11, font, or graphics
+    # libraries.
+    sources -= [
+      "filters/default_renderer_factory.cc",
+      "filters/default_renderer_factory.h",
+      "filters/gpu_video_decoder.cc",
+      "filters/gpu_video_decoder.h",
+      "filters/skcanvas_video_renderer.cc",
+      "filters/skcanvas_video_renderer.h",
+      "video/capture/fake_video_capture_device.cc",
+      "video/capture/fake_video_capture_device.h",
+      "video/capture/fake_video_capture_device_factory.h",
+      "video/capture/fake_video_capture_device_factory.cc",
+      "video/capture/file_video_capture_device_factory.h",
+      "video/capture/file_video_capture_device_factory.cc",
+      "video/capture/linux/video_capture_device_factory_linux.cc",
+      "video/capture/linux/video_capture_device_factory_linux.h",
+      "video/capture/video_capture_device_factory.cc",
+      "video/capture/video_capture_device_factory.h",
+    ]
+
+    deps -= [
+      "//skia",
+      "//ui/events:events_base",
+      "//ui/gfx",
+    ]
+  }
 }
 
 # Minimal media component for media/cast on iOS.
 if (is_ios) {
   component("media_for_cast_ios") {
     configs += [ ":media_config" ]
     all_dependent_configs = [ ":media_dependent_config" ]
     include_dirs = [ "." ]
     libs = [ "CoreVideo.framework" ]
 
@@ skipping 275 matching lines @@
     deps = [
       ":media",
       ":shared_memory_support",
       "//base",
       "//ui/gl",
       "//ui/gfx",
       "//ui/gfx/geometry",
     ]
   }
 }