Prepare for building with enable_app_list=0 on Desktop

chrome/browser/ui/BUILD.gn

Index: chrome/browser/ui/BUILD.gn
diff --git a/chrome/browser/ui/BUILD.gn b/chrome/browser/ui/BUILD.gn
index 771b6dbb2ed017ab918ea9df187c709740bd1a6f..01851a610c8d040c1732b2d1ca443efc74effabd 100644
--- a/chrome/browser/ui/BUILD.gn
+++ b/chrome/browser/ui/BUILD.gn
@@ -465,7 +465,6 @@ source_set("ui") {
       "//third_party/iaccessible2",
       "//third_party/isimpledom",
       "//third_party/wtl",
-      "//ui/app_list",
       "//ui/base/ime",
       "//ui/events:dom_keycode_converter",
     ]
@@ -477,6 +476,9 @@ source_set("ui") {
         "webui/help/version_updater_basic.h",
       ]
     }
+    if (enable_app_list) {
+      deps += [ "//ui/app_list" ]
+    }
   } else {  # 'OS!="win"
     if (toolkit_views) {
       public_deps += [
@@ -529,6 +531,12 @@ source_set("ui") {
                              ".",
                              "//chrome")
     }
+    if (is_desktop_linux) {
+      sources +=
+          rebase_path(gypi_values.chrome_browser_ui_app_list_linux_sources,
+                      ".",
+                      "//chrome")
+    }
     if (!is_mac && !use_ash) {
       sources +=
           rebase_path(gypi_values.chrome_browser_ui_app_list_views_sources,