Android: Roll the latest aapt2 prebuilt to android_build_tools

This rolls the nightly build 637621 of aapt2 to enable the latest fix
for resource name collapsing on bundles.

Bug: 912804
Change-Id: I96f239d0a2739b70a82e5f5f29203b7146272528
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2144396
Commit-Queue: Mohamed Heikal <mheikal@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#760605}

DEPS

@@ -683,7 +683,7 @@ deps = {
       'packages': [
           {
               'package': 'chromium/third_party/android_build_tools/aapt2',
-              'version': 'LKH_DI44rZhQ4RkScMFQLGSJ4jZyuPcff0llITnq-i4C',
+              'version': 'UxU41ozMxmre3dhGh39z_YK_TVdbwv2OZiatfSTXVoMC',
           },
       ],
       'condition': 'checkout_android',

third_party/android_build_tools/aapt2/README.chromium

@@ -12,4 +12,4 @@ file that contains host-specific binaries, which must be extracted. They are
 distributed here as a CIPD package instead. See cipd.yaml for details.
 
 Local Modifications:
-Fetched prebuilt from go/aapt2-6143298 (version not yet published to maven).
+Fetched prebuilt from go/aapt2-6376216 (version not yet published to maven).