Give CSChromium its own bundle identifier.

Prior to this CL, CSChromium (clean skeleton) was sharing Chromium's.
This means we can now install both alongisde.

BUG=none
R=sdefresne@chromium.org,marq@chromium.org

Review-Url: https://codereview.chromium.org/2754203003
Cr-Commit-Position: refs/heads/master@{#457805}

ios/clean/chrome/app/BUILD.gn

@@ -40,7 +40,7 @@ ios_app_bundle("chrome_clean_skeleton") {
   bundle_deps = [ "//ios/chrome/app/resources" ]
 
   extra_substitutions = [
-    "CHROMIUM_BUNDLE_ID=$chromium_bundle_id",
+    "CHROMIUM_BUNDLE_ID=$output_name",
     "CHROMIUM_SHORT_NAME=$chromium_short_name",
     "CHROMIUM_URL_SCHEME_1=$url_unsecure_scheme",
     "CHROMIUM_URL_SCHEME_2=$url_secure_scheme",