Allow generation of a chromium outdirs when enable_extensions=false

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 3e5e5894efc92fc80bb782228f0e13cc92dc08cd..7b7f92fc85df05e1351b91e392fdfe22130d612f 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -101,8 +101,6 @@ group("gn_all") {
       "//chrome/test/chromedriver:chromedriver_unittests",
       "//components/sync/tools:sync_client",
       "//components/sync/tools:sync_listen_notifications",
-      "//extensions:extensions_browsertests",
-      "//extensions:extensions_unittests",
       "//gpu/gles2_conform_support:gles2_conform_test",
       "//gpu/khronos_glcts_support:khronos_glcts_test",
       "//jingle:jingle_unittests",
@@ -149,6 +147,13 @@ group("gn_all") {
       "//ui/accessibility:accessibility_unittests",
       "//ui/accessibility/extensions",
     ]
+
+    if (enable_extensions) {
+      deps += [
+        "//extensions:extensions_browsertests",
+        "//extensions:extensions_unittests",
+      ]
+    }
   }
 
   if (!is_ios && !is_fuchsia) {