[Build] Add third_party/androidx to Chromium DEPS

BUG=1064277

Change-Id: I48efb249b8b14eef85285e1590e586e9bf5383f8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2644821Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Commit-Queue: Peter Kotwicz <pkotwicz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#846343}

DEPS

@@ -677,6 +677,17 @@ deps = {
       'condition': 'checkout_android_native_support',
   },
 
+  'src/third_party/androidx': {
+    'packages': [
+      {
+          'package': 'chromium/third_party/androidx',
+          'version': 'zGdAyNdySwhTXOWTtAushFRKlDwCWGcYSWiaS2R5m8YC',
+      },
+    ],
+    'condition': 'checkout_android',
+    'dep_type': 'cipd',
+  },
+
   'src/third_party/android_support_test_runner': {
       'packages': [
           {