[chromium] Remove longer spelling for enable_chromium flag

Test: CQ
US-472 #comment

Change-Id: I08eff49c6657f2e1a06711dfb24d183061e334a2
diff --git a/runtime/chromium/chromium.gni b/runtime/chromium/chromium.gni
index 710062c..9e56a59 100644
--- a/runtime/chromium/chromium.gni
+++ b/runtime/chromium/chromium.gni
@@ -3,12 +3,8 @@
 # found in the LICENSE file.
 
 declare_args() {
-  enable_chromium_based_web_runner = false
-}
-
-declare_args() {
   # This enables a chromium-based web_runner implementation.
   # If this is set to false and web_runner_prototype is in the build, the
   # prototype version will be used instead to handle web requests.
-  enable_chromium = enable_chromium_based_web_runner
+  enable_chromium = false
 }
diff --git a/tests/web_runner_smoke_tests/BUILD.gn b/tests/web_runner_smoke_tests/BUILD.gn
index f49b483..e5eb8f7 100644
--- a/tests/web_runner_smoke_tests/BUILD.gn
+++ b/tests/web_runner_smoke_tests/BUILD.gn
@@ -32,7 +32,7 @@
   ]
 
   # This test only works with the chromium based web runner
-  if (enable_chromium_based_web_runner) {
+  if (enable_chromium) {
     tests = [
       {
         name = "web_runner_smoke_tests"