GN(android): Add scripts & runtime logic for installing _managed apks

base/BUILD.gn

Index: base/BUILD.gn
diff --git a/base/BUILD.gn b/base/BUILD.gn
index ccb580f1dab092a83d7307956864eabd033b4c53..619c38eb5ac54be9dab784225c3110e5dac418c0 100644
--- a/base/BUILD.gn
+++ b/base/BUILD.gn
@@ -1585,6 +1585,15 @@ if (is_android) {
     ]
 
     DEPRECATED_java_in_dir = "android/java/src"
+    if (is_debug) {
+      java_files = [
+        "android/java/debug_src/org/chromium/base/ManagedInstall.java",
+        "android/java/debug_src/org/chromium/base/Reflect.java",
+      ]
+    } else {
+      java_files =
+          [ "android/java/release_src/org/chromium/base/ManagedInstall.java" ]
+    }
 
     # A new version of NativeLibraries.java (with the actual correct values)
     # will be created when creating an apk.