Replace java_files with sources in //components/app_modal/android

Replace usages of java_files with sources in above gn files, and
automatically format.

This CL was uploaded by git cl split.

TBR=tedchoc@chromium.org

Bug: 1035074
Change-Id: Idce57785494009c4d740f82eaa43746c8a8285fb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1980955Reviewed-by: Natalie Chouinard <chouinard@chromium.org>
Commit-Queue: Natalie Chouinard <chouinard@chromium.org>
Auto-Submit: Natalie Chouinard <chouinard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#727219}

components/app_modal/android/BUILD.gn

@@ -7,7 +7,7 @@ import("//build/config/locales.gni")
 import("//ui/android/features.gni")
 
 android_library("java") {
-  java_files = [
+  sources = [
     "java/src/org/chromium/components/app_modal/JavascriptAppModalDialog.java",
     "java/src/org/chromium/components/app_modal/JavascriptDialogCustomView.java",
     "java/src/org/chromium/components/app_modal/JavascriptModalDialog.java",