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 51a5e40121df5eaf3082e471dac4bf797595fe74..4f46b8679b2ca6c73a85f61cc966e3fadd1fcfb2 100644
--- a/chrome/browser/ui/BUILD.gn
+++ b/chrome/browser/ui/BUILD.gn
@@ -455,7 +455,6 @@ source_set("ui") {
       "//third_party/iaccessible2",
       "//third_party/isimpledom",
       "//third_party/wtl",
-      "//ui/app_list",
       "//ui/base/ime",
       "//ui/events:dom_keycode_converter",
     ]
@@ -467,6 +466,9 @@ 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 += [
@@ -519,6 +521,12 @@ source_set("ui") {
                              ".",
                              "//chrome")
     }
+    if (is_desktop_linux) {
+      sources +=
+          rebase_path(gypi_values.chrome_browser_ui_app_list_linux_sources,
+                      ".",
+                      "//chrome")
+    }
     if (!is_mac) {
       sources +=
           rebase_path(gypi_values.chrome_browser_ui_app_list_views_sources,