Upgrade ArCore APK to 1.4

Regular upgrade to the current release version of ArCore.

TBR=vollick@chromium.org

Change-Id: I48dcf2c0cacbc0e09384c412889a898d852fcf88
Reviewed-on: https://chromium-review.googlesource.com/1226359Reviewed-by: Brian Sheedy <bsheedy@chromium.org>
Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#591392}

third_party/arcore-android-sdk/README.chromium

@@ -29,6 +29,7 @@ The LICENSE file is taken from
  * https://github.com/google-ar/arcore-unity-sdk/blob/master/LICENSE
 
 Changes:
+2018-09-14 - Upgrade test-apks/arcore_current.apk to v1.4.
 2018-08-10 - First, removed arcore shim copy target from BUILD.gn since it is no
              longer needed. Second, added zero-byte dummy arcore library for AR
              module support.

third_party/arcore-android-sdk/test-apks/arcore/apk_version_history.txt

 v1.3 f8004b83fc757d7724abdd492ac74cd7a9ab8e62
+v1.4 9c3ea648b0e3d1a5f837477f3efb02f87e305c0f

third_party/arcore-android-sdk/test-apks/arcore/arcore_current.apk.sha1

-f8004b83fc757d7724abdd492ac74cd7a9ab8e62
+9c3ea648b0e3d1a5f837477f3efb02f87e305c0f
\ No newline at end of file