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 a4e5a5c028da25da06f1b5202a6cd67456d6a6f6..27e714cfab2eb9ec22996818f88edfe7c2b83d51 100644
--- a/base/BUILD.gn
+++ b/base/BUILD.gn
@@ -1596,6 +1596,14 @@ if (is_android) {
     ]
 
     DEPRECATED_java_in_dir = "android/java/src"
+    if (is_debug) {
+      java_files = [
+        "android/java/debug_src/org/chromium/base/IncrementalInstall.java",
+        "android/java/debug_src/org/chromium/base/Reflect.java",
+      ]
+    } else {
+      java_files = [ "android/java/release_src/org/chromium/base/IncrementalInstall.java" ]
+    }
 
     # A new version of NativeLibraries.java (with the actual correct values)
     # will be created when creating an apk.