gn: simplify dbus logic in device/battery

device/battery/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("//mojo/public/tools/bindings/mojom.gni")
 
 # On android, BatteryManager mojo service is implemented directly in Java.
 if (!is_android) {
   component("battery") {
@@ skipping 28 matching lines @@
     if (is_chromeos) {
       configs += [ "//build/config/linux:dbus" ]
       deps += [
         "//chromeos:chromeos",
         "//chromeos:power_manager_proto",
       ]
       sources -= [
         "battery_status_manager_default.cc",
         "battery_status_manager_linux.cc",
       ]
-    }
-
-    if (is_desktop_linux) {
+    } else if (is_linux && !is_chromeos) {

[timvolodine, 2016/02/10 12:40:40]

can we just have a separate "if (is_linux &&!is_chrome_os)" without the "else"
because the "!is_chromeos" is kind of redundant with the "else if". For
readability I think it's good to keep the system sections as separate "ifs" as
we have for all other mac and win below.

[Mostyn Bramley-Moore, 2016/02/10 13:01:51]

Done.

       if (use_dbus) {
         configs += [ "//build/config/linux:dbus" ]
         deps += [ "//dbus" ]
         sources -= [ "battery_status_manager_default.cc" ]
       } else {
         sources -= [ "battery_status_manager_linux.cc" ]
       }
     }
 
     if (is_mac) {
       sources -= [ "battery_status_manager_default.cc" ]
     }
 
     if (is_win) {
       sources -= [ "battery_status_manager_default.cc" ]
     }
   }
 }
 
 mojom("mojo_bindings") {
   sources = [
     "battery_monitor.mojom",
     "battery_status.mojom",
   ]
 }