Docs: Updating ANDROID_ID information to reflect Android O changes.

Bug: 38270718

Test: Verified on local build.

Change-Id: If4f86d261ae950cc14579aeba65c36a289cdf56c

diff --git a/core/java/android/provider/Settings.java b/core/java/android/provider/Settings.java
index b7514fd..26f9cd9 100755 (executable)
--- a/core/java/android/provider/Settings.java
+++ b/core/java/android/provider/Settings.java
@@ -5106,17 +5106,39 @@ public final class Settings {
         public static final String ALLOW_MOCK_LOCATION = "mock_location";
 
         /**
-         * A 64-bit number (as a hex string) that is randomly
+         * On Android 8.0 (API level 26) and higher versions of the platform,
+         * a 64-bit number (expressed as a hexadecimal string), unique to
+         * each combination of app-signing key, user, and device.
+         * Values of {@code ANDROID_ID} are scoped by signing key and user.
+         * The value may change if a factory reset is performed on the
+         * device or if an APK signing key changes.
+         *
+         * For more information about how the platform handles {@code ANDROID_ID}
+         * in Android 8.0 (API level 26) and higher, see <a
+         * href="{@docRoot}preview/behavior-changes.html#privacy-all">
+         * Android 8.0 Behavior Changes</a>.
+         *
+         * <p class="note"><strong>Note:</strong> For apps that were installed
+         * prior to updating the device to a version of Android 8.0
+         * (API level 26) or higher, the value of {@code ANDROID_ID} changes
+         * if the app is uninstalled and then reinstalled after the OTA.
+         * To preserve values across uninstalls after an OTA to Android 8.0
+         * or higher, developers can use
+         * <a href="{@docRoot}guide/topics/data/keyvaluebackup.html">
+         * Key/Value Backup</a>.</p>
+         *
+         * <p>In versions of the platform lower than Android 8.0 (API level 26),
+         * a 64-bit number (expressed as a hexadecimal string) that is randomly
          * generated when the user first sets up the device and should remain
-         * constant for the lifetime of the user's device. The value may
-         * change if a factory reset is performed on the device.
-         * <p class="note"><strong>Note:</strong> When a device has <a
-         * href="{@docRoot}about/versions/android-4.2.html#MultipleUsers">multiple users</a>
-         * (available on certain devices running Android 4.2 or higher), each user appears as a
-         * completely separate device, so the {@code ANDROID_ID} value is unique to each
-         * user.</p>
-         *
-         * <p class="note"><strong>Note:</strong> If the caller is an Instant App the id is scoped
+         * constant for the lifetime of the user's device.
+         *
+         * On devices that have
+         * <a href="{@docRoot}about/versions/android-4.2.html#MultipleUsers">
+         * multiple users</a>, each user appears as a
+         * completely separate device, so the {@code ANDROID_ID} value is
+         * unique to each user.</p>
+         *
+         * <p class="note"><strong>Note:</strong> If the caller is an Instant App the ID is scoped
          * to the Instant App, it is generated when the Instant App is first installed and reset if
          * the user clears the Instant App.
          */