Prepare for building with enable_app_list=0 on Desktop

chrome/browser/ui/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/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//chrome/common/features.gni")
 
 gypi_values = exec_script("//build/gypi_to_gn.py",
@@ skipping 432 matching lines @@
       "//ui/views",
       "//ui/views/controls/webview",
     ]
     deps += [
       "//chrome/installer/util:strings",
       "//components/search_engines",
       "//google_update",
       "//third_party/iaccessible2",
       "//third_party/isimpledom",
       "//third_party/wtl",
-      "//ui/app_list",
       "//ui/base/ime",
       "//ui/events:dom_keycode_converter",
     ]
     if (!is_chrome_branded) {
       deps -= [ "//google_update" ]
       sources -= [ "webui/help/version_updater_win.cc" ]
       sources += [
         "webui/help/version_updater_basic.cc",
         "webui/help/version_updater_basic.h",
       ]
     }
+    if (enable_app_list) {
+      deps += [ "//ui/app_list" ]
+    }
   } else {  # 'OS!="win"
     if (toolkit_views) {
       public_deps += [
         "//ui/views",
         "//ui/views/controls/webview",
       ]
     }
   }
   if (is_desktop_linux) {
     sources += rebase_path(gypi_values.chrome_browser_ui_desktop_linux_sources,
@@ skipping 32 matching lines @@
 
   if (enable_app_list) {
     sources += rebase_path(gypi_values.chrome_browser_ui_app_list_sources,
                            ".",
                            "//chrome")
     if (is_chromeos) {
       sources += rebase_path(gypi_values.chrome_browser_ui_chromeos_arc_sources,
                              ".",
                              "//chrome")
     }
+    if (is_desktop_linux) {

[Matt Giuca, 2016/05/03 07:31:16]

Can you explain what this is doing?

[tapted, 2016/05/04 09:55:43]

This is adding the app_list_linux_sources - i.e. those 4 files from
chrome_browser_ui.gypi for desktop linux but not ChromeOS --
app_list_{service_,}linux.{cc,h} -- which were previously in 

# Desktop Linux. Assume aura/ash/views/x11.
'chrome_browser_ui_desktop_linux_sources': [
  /* here */


I think this fits the common pattern, but holler if you think it needs a comment
in the .gn file

[Matt Giuca, 2016/05/05 00:26:30]

Acknowledged.

+      sources +=
+          rebase_path(gypi_values.chrome_browser_ui_app_list_linux_sources,
+                      ".",
+                      "//chrome")
+    }
+    if (!is_mac) {
+      sources +=
+          rebase_path(gypi_values.chrome_browser_ui_app_list_views_sources,
+                      ".",
+                      "//chrome")
+    }
     deps += [ "//ui/app_list" ]
   } else {
     sources += rebase_path(gypi_values.chrome_browser_ui_non_app_list_sources,
                            ".",
                            "//chrome")
   }
   if (enable_autofill_dialog) {
     sources +=
         rebase_path(gypi_values.chrome_browser_ui_autofill_dialog_sources,
                     ".",
@@ skipping 139 matching lines @@
     "//chrome/browser",
     "//content/public/browser",
     "//content/public/common",
     "//content/test:test_support",
     "//net:test_support",
     "//skia",
     "//testing/gtest",
     "//ui/base",
   ]
 }