Show Launcher's widget picker in an activity.

Bug: 307306823
Test: atest Launcher3Tests
Flag: NA

Change-Id: I28ef731abcdf1bd44c66366d42a135912dbcc5be
diff --git a/quickstep/AndroidManifest.xml b/quickstep/AndroidManifest.xml
index 82f8ebe..db46508 100644
--- a/quickstep/AndroidManifest.xml
+++ b/quickstep/AndroidManifest.xml
@@ -43,6 +43,10 @@
 
     <uses-permission android:name="android.permission.SYSTEM_APPLICATION_OVERLAY" />
 
+    <!-- Permission required to start a WidgetPickerActivity. -->
+    <permission android:name="${packageName}.permission.START_WIDGET_PICKER_ACTIVITY"
+        android:protectionLevel="signature|privileged" />
+
     <application android:backupAgent="com.android.launcher3.LauncherBackupAgent"
          android:fullBackupOnly="true"
          android:fullBackupContent="@xml/backupscheme"
@@ -133,6 +137,20 @@
             </intent-filter>
         </activity>
 
+        <activity android:name="com.android.launcher3.WidgetPickerActivity"
+            android:theme="@style/WidgetPickerActivityTheme"
+            android:excludeFromRecents="true"
+            android:autoRemoveFromRecents="true"
+            android:showOnLockScreen="true"
+            android:launchMode="singleTop"
+            android:exported="true"
+            android:permission="android.permission.START_WIDGET_PICKER_ACTIVITY">
+            <intent-filter>
+                <action android:name="android.intent.action.PICK" />
+                <category android:name="android.intent.category.DEFAULT" />
+            </intent-filter>
+        </activity>
+
     </application>
 
 </manifest>