Bump minSdk to 21

Test: presubmit
Bug: 322508920
Bug: 329997430
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:1448a452b523404d442ebd02fd5d2c0241ce8609)
Merged-In: I080e1ab31139379423e74e44ff3fa76b36becbb3
Change-Id: I080e1ab31139379423e74e44ff3fa76b36becbb3
diff --git a/Android.bp b/Android.bp
index f9fc433..8a4196a 100644
--- a/Android.bp
+++ b/Android.bp
@@ -100,7 +100,7 @@
         "androidx.window_window",
         "error_prone_annotations",
     ],
-    min_sdk_version: "19",
+    min_sdk_version: "21",
     sdk_version: "current",
     optimize: {
         proguard_flags_files: ["proguard.flags"],
@@ -128,7 +128,7 @@
         "androidx.window_window",
         "error_prone_annotations",
     ],
-    min_sdk_version: "19",
+    min_sdk_version: "21",
     sdk_version: "current",
     optimize: {
         proguard_flags_files: ["proguard.flags"],