Android 2.3.3 source, you can download it and see what, hope to help.

android_src_2.3.3
.................\android
.................\.......\accessibilityservice
.................\.......\....................\AccessibilityService.java
.................\.......\....................\AccessibilityServiceInfo.aidl
.................\.......\....................\AccessibilityServiceInfo.java
.................\.......\....................\IAccessibilityServiceConnection.aidl
.................\.......\....................\IEventListener.aidl
.................\.......\accounts
.................\.......\........\AbstractAccountAuthenticator.java
.................\.......\........\Account.aidl
.................\.......\........\Account.java
.................\.......\........\AccountAuthenticatorActivity.java
.................\.......\........\AccountAuthenticatorCache.java
.................\.......\........\AccountAuthenticatorResponse.java
.................\.......\........\AccountManager.java
.................\.......\........\AccountManagerCallback.java
.................\.......\........\AccountManagerFuture.java
.................\.......\........\AccountManagerResponse.java
.................\.......\........\AccountManagerService.java
.................\.......\........\AccountsException.java
.................\.......\........\AuthenticatorDescription.aidl
.................\.......\........\AuthenticatorDescription.java
.................\.......\........\AuthenticatorException.java
.................\.......\........\ChooseAccountActivity.java
.................\.......\........\GrantCredentialsPermissionActivity.java
.................\.......\........\IAccountAuthenticator.aidl
.................\.......\........\IAccountAuthenticatorResponse.aidl
.................\.......\........\IAccountManager.aidl
.................\.......\........\IAccountManagerResponse.aidl
.................\.......\........\NetworkErrorException.java
.................\.......\........\OnAccountsUpdateListener.java
.................\.......\........\OperationCanceledException.java
.................\.......\annotation
.................\.......\..........\SdkConstant.java
.................\.......\..........\Widget.java
.................\.......\app
.................\.......\appwidget
.................\.......\.........\AppWidgetHost.java
.................\.......\.........\AppWidgetHostView.java
.................\.......\.........\AppWidgetManager.java
.................\.......\.........\AppWidgetProvider.java
.................\.......\.........\AppWidgetProviderInfo.aidl
.................\.......\.........\AppWidgetProviderInfo.java
.................\.......\.........\package.html
.................\.......\...\Activity.java
.................\.......\...\ActivityGroup.java
.................\.......\...\ActivityManager.java
.................\.......\...\ActivityManagerNative.java
.................\.......\...\ActivityThread.java
.................\.......\...\admin
.................\.......\...\.....\DeviceAdminInfo.java
.................\.......\...\.....\DeviceAdminReceiver.java
.................\.......\...\.....\DevicePolicyManager.java
.................\.......\...\.....\IDevicePolicyManager.aidl
.................\.......\...\AlarmManager.java
.................\.......\...\AlertDialog.java
.................\.......\...\AliasActivity.java
.................\.......\...\AppGlobals.java
.................\.......\...\Application.java
.................\.......\...\ApplicationErrorReport.java
.................\.......\...\ApplicationLoaders.java
.................\.......\...\ApplicationThreadNative.java
.................\.......\...\backup
.................\.......\...\......\AbsoluteFileBackupHelper.java
.................\.......\...\......\BackupAgent.java
.................\.......\...\......\BackupAgentHelper.java
.................\.......\...\......\BackupDataInput.java
.................\.......\...\......\BackupDataInputStream.java
.................\.......\...\......\BackupDataOutput.java
.................\.......\...\......\BackupHelper.java
.................\.......\...\......\BackupHelperDispatcher.java
.................\

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