Enable strict checks for {virtual,override,final} on CrOS.

BUG=417463

Review URL: https://codereview.chromium.org/873883003

Cr-Commit-Position: refs/heads/master@{#312996}

build/common.gypi

@@ -2143,7 +2143,7 @@
         'conditions': [
           # TODO(dcheng): https://crbug.com/417463 -- work to enable this flag
           # on all platforms is currently underway.
-          ['(OS=="linux" and chromeos==0) or OS=="mac" or OS=="ios"', {
+          ['OS=="linux" or OS=="mac" or OS=="ios"', {
             'clang_chrome_plugins_flags': [
               '-Xclang',
               '-plugin-arg-find-bad-constructs',