chromeos: removes special casing of ChromeOS

In hopes of having base::debug::Alias work better on ChromeOS.

BUG=867035
TEST=none

Change-Id: I509efc3bcafe71beaa86c9f5180043255e3ec3db
Reviewed-on: https://chromium-review.googlesource.com/1219889Reviewed-by: Nico Weber <thakis@chromium.org>
Reviewed-by: Reid Kleckner <rnk@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#592864}

build/config/compiler/BUILD.gn

@@ -501,8 +501,7 @@ config("compiler") {
     }
   }
 
-  if (is_clang && !is_nacl && current_toolchain == host_toolchain &&
-      target_os != "chromeos") {
+  if (is_clang && !is_nacl && !use_xcode_clang) {
     cflags += [
       # TODO(hans): Remove this once Clang generates better optimized debug info
       # by default. https://crbug.com/765793