Skip 'dep:chrome_internal' Tast tests if we're not building w/ is_chrome_branded.

So that no dep:chrome_internal tests are ran if they don't have the
needed internal bits.

Bug: 947531
Change-Id: I060734d2fe05c878d16f2c6a63815bd0abbb554c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1637644Reviewed-by: Dan Erat <derat@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Ben Pastene <bpastene@chromium.org>
Cr-Commit-Position: refs/heads/master@{#665158}

build/config/chromeos/rules.gni

@@ -2,6 +2,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/chrome_build.gni")
+
 assert(is_chromeos)
 
 declare_args() {
@@ -204,8 +206,14 @@ template("tast_test") {
 
   # Default the expression to match any chrome-related test.
   if (!defined(tast_attr_expr) && !defined(tast_tests)) {
+    # The following expression filters out all non-critical tests. See the link
+    # below for more details:
+    # https://chromium.googlesource.com/chromiumos/platform/tast/+/master/docs/test_attributes.md
     tast_attr_expr =
-        "!disabled && !\"group:*\" && !informational" + " && (\"dep:chrome\")"
+        "!disabled && !\"group:*\" && !informational && \"dep:chrome\""
+    if (!is_chrome_branded) {
+      tast_attr_expr += " && \"!dep:chrome_internal\""
+    }
   } else {
     assert(defined(tast_attr_expr) != defined(tast_tests),
            "Specify one of tast_tests or tast_attr_expr.")