Rename is_chromeos in chrome/src.

chrome/BUILD.gn

Index: chrome/BUILD.gn
diff --git a/chrome/BUILD.gn b/chrome/BUILD.gn
index 046b68779a1fa8206e0601f52e9e86f7c57060b1..2bfa1a84d6065d7b181fd414fdba2fbdcdc04b50 100644
--- a/chrome/BUILD.gn
+++ b/chrome/BUILD.gn
@@ -444,7 +444,7 @@ group("extra_resources") {
     ]
   }
 
-  if (is_chromeos) {
+  if (use_cros_fe) {
     deps += [ "//chrome/browser/resources/chromeos/chromevox" ]
   }
 
@@ -563,7 +563,7 @@ repack("packed_extra_resources") {
       "//third_party/WebKit/public:resources",
     ]
   }
-  if (is_chromeos) {
+  if (use_cros_fe) {
     sources += [ "$root_gen_dir/ui/file_manager/file_manager_resources.pak" ]
     deps += [ "//ui/file_manager:resources" ]
   }
@@ -687,7 +687,7 @@ template("chrome_repack_percent") {
       sources += [ "$root_gen_dir/ui/views/resources/views_resources_${percent}_percent.pak" ]
       deps += [ "//ui/views/resources" ]
     }
-    if (is_chromeos) {
+    if (use_cros_fe) {
       sources += [ "$root_gen_dir/ui/chromeos/resources/ui_chromeos_resources_${percent}_percent.pak" ]
       deps += [ "//ui/chromeos/resources" ]
     }