Add support for heavy-weight applications.

Only one can be running at a time, their process can not be killed,
and a notification is posted while it is running.

Change-Id: I843015723947e0c934ae63a1aeee139327c0bc01
diff --git a/core/res/AndroidManifest.xml b/core/res/AndroidManifest.xml
index 2a2208f..1fcf186 100644
--- a/core/res/AndroidManifest.xml
+++ b/core/res/AndroidManifest.xml
@@ -1250,6 +1250,12 @@
                 <category android:name="android.intent.category.DEFAULT" />
             </intent-filter>
         </activity>
+        <activity android:name="com.android.internal.app.HeavyWeightSwitcherActivity"
+                android:theme="@style/Theme.Dialog"
+                android:label="@string/heavy_weight_switcher_title"
+                android:finishOnCloseSystemDialogs="true"
+                android:excludeFromRecents="true">
+        </activity>
         <activity android:name="com.android.internal.app.DisableCarModeActivity"
                 android:theme="@style/Theme.NoDisplay"
                 android:excludeFromRecents="true">