Disable building the APK when a prebuilt is in use.

If the product is configured to use a prebuilt webview APK, don't
attempt to build it from source to avoid a duplicate definition.

Bug: 16870861
Change-Id: I689cda55ef75c843bca2aa020df1b4cefd8821dc
(cherry picked from commit c182da21c498c2b3f143e9b775f89a7aeb9be6ce)
1 file changed
tree: 5ef19693e5cfec5c595eb96af7d2e291e23d9e1a
  1. Android.mk
  2. chromium/
  3. nullwebview/