[chromium] Enable chromium by default

This changes the default web runner component to chromium.

Test: CQ, view auth screen, 'tiles_ctl add https://google.com'
US-472 #comment switch default to chromium enabled

Change-Id: I2c826c4ee1983a5f2b8dcb19b0a0ae6dc7a79d2b
diff --git a/runtime/chromium/chromium.gni b/runtime/chromium/chromium.gni
index 9e56a59..cd991f6 100644
--- a/runtime/chromium/chromium.gni
+++ b/runtime/chromium/chromium.gni
@@ -6,5 +6,5 @@
   # 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 = false
+  enable_chromium = true
 }