Add Context.createContextAsUser()

Without it, apps (mainline modules) will need to use createPackageContext...,
which is a bit painful.

Bug: 142472686
Test: atest android.content.cts.ContextTest#testCreateContextAsUser
Change-Id: Id640e03862462724df1a4a3101f0b08faafba22f

api/system-current.txt

@@ -1358,8 +1358,9 @@ package android.content {
   public abstract class Context {
     method @RequiresPermission(android.Manifest.permission.INTERACT_ACROSS_USERS) public boolean bindServiceAsUser(@RequiresPermission android.content.Intent, android.content.ServiceConnection, int, android.os.UserHandle);
+    method @NonNull public android.content.Context createContextAsUser(@NonNull android.os.UserHandle);
     method public abstract android.content.Context createCredentialProtectedStorageContext();
-    method public android.content.Context createPackageContextAsUser(String, int, android.os.UserHandle) throws android.content.pm.PackageManager.NameNotFoundException;
+    method @NonNull public android.content.Context createPackageContextAsUser(@NonNull String, int, @NonNull android.os.UserHandle) throws android.content.pm.PackageManager.NameNotFoundException;
     method @Nullable public abstract java.io.File getPreloadsFileCache();
     method public abstract boolean isCredentialProtectedStorage();
     method public abstract void sendBroadcast(android.content.Intent, @Nullable String, @Nullable android.os.Bundle);

api/test-current.txt

@@ -659,7 +659,8 @@ package android.content {
   }
 
   public abstract class Context {
-    method public android.content.Context createPackageContextAsUser(String, int, android.os.UserHandle) throws android.content.pm.PackageManager.NameNotFoundException;
+    method @NonNull public android.content.Context createContextAsUser(@NonNull android.os.UserHandle);
+    method @NonNull public android.content.Context createPackageContextAsUser(@NonNull String, int, @NonNull android.os.UserHandle) throws android.content.pm.PackageManager.NameNotFoundException;
     method public abstract android.view.Display getDisplay();
     method public abstract int getDisplayId();
     method public android.os.UserHandle getUser();

core/java/android/app/ContextImpl.java

@@ -2202,6 +2202,15 @@ class ContextImpl extends Context {
                 "Application package " + packageName + " not found");
     }
 
+    @Override
+    public Context createContextAsUser(UserHandle user) {
+        try {
+            return createPackageContextAsUser(getPackageName(), mFlags, user);
+        } catch (NameNotFoundException e) {
+            throw new IllegalStateException("Own package not found: package=" + getPackageName());
+        }
+    }
+
     @Override
     public Context createContextForSplit(String splitName) throws NameNotFoundException {
         if (!mPackageInfo.getApplicationInfo().requestsIsolatedSplitLoading()) {

core/java/android/content/Context.java

@@ -5217,8 +5217,9 @@ public abstract class Context {
      */
     @SystemApi
     @TestApi
+    @NonNull
     public Context createPackageContextAsUser(
-            String packageName, @CreatePackageOptions int flags, UserHandle user)
+            @NonNull String packageName, @CreatePackageOptions int flags, @NonNull UserHandle user)
             throws PackageManager.NameNotFoundException {
         if (Build.IS_ENG) {
             throw new IllegalStateException("createPackageContextAsUser not overridden!");
@@ -5226,6 +5227,23 @@ public abstract class Context {
         return this;
     }
 
+    /**
+     * Similar to {@link #createPackageContext(String, int)}, but for the own package with a
+     * different {@link UserHandle}. For example, {@link #getContentResolver()}
+     * will open any {@link Uri} as the given user.
+     *
+     * @hide
+     */
+    @SystemApi
+    @TestApi
+    @NonNull
+    public Context createContextAsUser(@NonNull UserHandle user) {
+        if (Build.IS_ENG) {
+            throw new IllegalStateException("createContextAsUser not overridden!");
+        }
+        return this;
+    }
+
     /**
      * Creates a context given an {@link android.content.pm.ApplicationInfo}.
      *

core/java/android/content/ContextWrapper.java

@@ -883,6 +883,12 @@ public class ContextWrapper extends Context {
         return mBase.createPackageContextAsUser(packageName, flags, user);
     }
 
+    /** @hide */
+    @Override
+    public Context createContextAsUser(UserHandle user) {
+        return mBase.createContextAsUser(user);
+    }
+
     /** @hide */
     @Override
     @UnsupportedAppUsage

test-mock/src/android/test/mock/MockContext.java

@@ -756,6 +756,12 @@ public class MockContext extends Context {
         throw new UnsupportedOperationException();
     }
 
+    /** {@hide} */
+    @Override
+    public Context createContextAsUser(UserHandle user) {
+        throw new UnsupportedOperationException();
+    }
+
     /** {@hide} */
     @Override
     public int getUserId() {