Don't base android lint version off of android sdk version.

If downstream overrides sdk version, we don't want the lint version to
change.

BUG=623989

Review-Url: https://codereview.chromium.org/2418433003
Cr-Original-Commit-Position: refs/heads/master@{#424847}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 11837e363c671aa15024b9d1228057fc2bacd6eb

config/android/config.gni

@@ -40,8 +40,10 @@ if (is_android) {
   }
 
   if (!defined(default_lint_android_sdk_root)) {
-    default_lint_android_sdk_root = default_android_sdk_root
-    default_lint_android_sdk_version = default_android_sdk_version
+    # Purposefully repeated so that downstream can change
+    # default_android_sdk_root without changing lint version.
+    default_lint_android_sdk_root = "//third_party/android_tools/sdk"
+    default_lint_android_sdk_version = "23"
   }
 
   if (!defined(default_android_keystore_path)) {