Comment more on component callback order for N+ OS

This CL attempts to clarify that just having a ContentProvider does
not necessarily mean ContentProvider#onCreate() is always called
before Application#onCreate() on Android N and later devices because
of direct boot.

Fix: 67559645
Test: make -j doc-comment-check-docs
Change-Id: I33b7cda42146333f48fb445027f5d31f3c5af5b6

1 files changed, 13 insertions, 3 deletions

diff --git a/core/java/android/app/Application.java b/core/java/android/app/Application.java
index 5822f5c8f6c1..5a739ea6d3e4 100644
--- a/core/java/android/app/Application.java
+++ b/core/java/android/app/Application.java
@@ -86,11 +86,21 @@ public class Application extends ContextWrapper implements ComponentCallbacks2 {
     /**
      * Called when the application is starting, before any activity, service,
      * or receiver objects (excluding content providers) have been created.
-     * Implementations should be as quick as possible (for example using
+     *
+     * <p>Implementations should be as quick as possible (for example using
      * lazy initialization of state) since the time spent in this function
      * directly impacts the performance of starting the first activity,
-     * service, or receiver in a process.
-     * If you override this method, be sure to call super.onCreate().
+     * service, or receiver in a process.</p>
+     *
+     * <p>If you override this method, be sure to call {@code super.onCreate()}.</p>
+     *
+     * <p class="note">Be aware that direct boot may also affect callback order on
+     * Android {@link android.os.Build.VERSION_CODES#N} and later devices.
+     * Until the user unlocks the device, only direct boot aware components are
+     * allowed to run. You should consider that all direct boot unaware
+     * components, including such {@link android.content.ContentProvider}, are
+     * disabled until user unlock happens, especially when component callback
+     * order matters.</p>
      */
     @CallSuper
     public void onCreate() {