components: Add Exosphere component.

chrome/browser/ui/views/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/ui.gni")
 
 assert(toolkit_views)
 
 component("views") {
   output_name = "browser_ui_views"
@@ skipping 18 matching lines @@
     "//base",
     "//skia",
     "//ui/base",
     "//ui/events",
     "//ui/gfx",
     "//ui/gfx/geometry",
     "//url",
   ]
 
   if (use_ash) {
-    deps += [ "//ash" ]
+    deps += [
+      "//ash",
+      "//components/exo",
+    ]
+    if (is_linux) {

[piman, 2015/11/17 02:43:53]

Do we need this on anything but chromeos at this point? It pulls in a bunch of
deps, and I'd prefer to avoid bloat.

Maybe we could define a use_exosphere option / USE_EXOSPHERE define so that it's
easy to enable selectively, and we can bring it on linux later.

[reveman, 2015/11/17 18:04:04]

Fyi, this only pulls in //third_party/wayland:wayland_server and that's ~4k
lines of C code and the .a that we produce for that is only 3450 bytes on my x64
machine.
use_exosphere sgtm. I'll add that as a last step when everything else looks
good. It's nice to not have any artificial build constraints and verify that
this builds and runs on all platforms and all configurations possible while
making changes but it doesn't make sense to land that.

[reveman, 2015/11/18 00:21:47]

Added enable_wayland_server option to latest patch now that I know that this
builds and runs on all possible configurations. I think enable_wayland_server
makes more sense than use_exosphere as exosphere is just a dependency required
to provide wayland server support. enable_wayland_server = is_chromeos by
default but can be enabled on linux.

+      deps += [ "//components/exo/wayland" ]
+    }
   }
 }