Add completion handler for ScreenshotHelper

The Next-Generation Assistant can call SysUI to request a screenshot.
Adding an indicator that a screenshot has completed successfully enables
the Next-Generation Assistant to show the assistant UI again once the
screenshot has completed.

Bug: 137201206
Bug: 131082115
Test: Wired up SysUIG's NGA integration's touch outside handler to call
take screenshot, confirmed it behaved as expected when a touch outside
occurred.
Change-Id: Ie83af6c9dd8e93b3e18a820d79c02125a19bd62a
diff --git a/packages/SystemUI/src/com/android/systemui/globalactions/GlobalActionsDialog.java b/packages/SystemUI/src/com/android/systemui/globalactions/GlobalActionsDialog.java
index 0e4c155..ff02e71 100644
--- a/packages/SystemUI/src/com/android/systemui/globalactions/GlobalActionsDialog.java
+++ b/packages/SystemUI/src/com/android/systemui/globalactions/GlobalActionsDialog.java
@@ -614,7 +614,7 @@
             mHandler.postDelayed(new Runnable() {
                 @Override
                 public void run() {
-                    mScreenshotHelper.takeScreenshot(1, true, true, mHandler);
+                    mScreenshotHelper.takeScreenshot(1, true, true, mHandler, null);
                     MetricsLogger.action(mContext,
                             MetricsEvent.ACTION_SCREENSHOT_POWER_MENU);
                 }