Fixes nav stack issue.

By marking the Intent that's being sent to WPP as "launched from
settings", the code in CustomizationPickerActivity can correctly
conclude that the multi-pane wrapper does not need to be applied to the
intent, preventing the odd "disordering" of the back stack in the bug.

Fix: 284809020
Test: manually verified, on a large screen device with a multi-pane
settings configuration, that going to Display > Lock screen > Shortcuts
and then swiping back off the left edge of the display correctly exits
settings instead of revealing an incorrect screen like it did in the
bug.
Test: also manually verified that the long-press on the home screena and
on the lock screen paths both open the right tab in WPP in settings
correctly.

Change-Id: Iac2b4e9fa5bab91b6a5251f1c51b4d21a0824f00

src/com/android/settings/display/CustomizableLockScreenUtils.java

@@ -60,6 +60,12 @@ public final class CustomizableLockScreenUtils {
     @VisibleForTesting
     static final String AFFORDANCE_NAME = "affordance_name";
 
+    @VisibleForTesting
+    static final String WALLPAPER_LAUNCH_SOURCE = "com.android.wallpaper.LAUNCH_SOURCE";
+    @VisibleForTesting
+    static final String LAUNCH_SOURCE_SETTINGS = "app_launched_settings";
+
+
     private CustomizableLockScreenUtils() {}
 
     /**
@@ -163,7 +169,14 @@ public final class CustomizableLockScreenUtils {
      * activity.
      */
     public static Intent newIntent() {
-        return new Intent(Intent.ACTION_SET_WALLPAPER);
+        final Intent intent = new Intent(Intent.ACTION_SET_WALLPAPER);
+        // By adding the launch source here, we tell our destination (in this case, the wallpaper
+        // picker app) that it's been launched from within settings. That way, if we are in a
+        // multi-pane configuration (for example, for large screens), the wallpaper picker app can
+        // safely skip redirecting to the multi-pane version of its activity, as it's already opened
+        // within a multi-pane configuration context.
+        intent.putExtra(WALLPAPER_LAUNCH_SOURCE, LAUNCH_SOURCE_SETTINGS);
+        return intent;
     }
 
     private static boolean isWallpaperPickerInstalled(Context context) {

tests/robotests/src/com/android/settings/display/CustomizableLockScreenQuickAffordancesPreferenceControllerTest.java

@@ -114,6 +114,9 @@ public class CustomizableLockScreenQuickAffordancesPreferenceControllerTest {
         assertThat(intentCaptor.getValue().getPackage()).isEqualTo(
                 mContext.getString(R.string.config_wallpaper_picker_package));
         assertThat(intentCaptor.getValue().getAction()).isEqualTo(Intent.ACTION_SET_WALLPAPER);
+        assertThat(intentCaptor.getValue().getStringExtra(
+                CustomizableLockScreenUtils.WALLPAPER_LAUNCH_SOURCE)).isEqualTo(
+                        CustomizableLockScreenUtils.LAUNCH_SOURCE_SETTINGS);
         assertThat(intentCaptor.getValue().getStringExtra("destination"))
                 .isEqualTo("quick_affordances");
     }