Adding callback to notify LauncherCallbacks when quickstep starts

Bug: 73081875
Change-Id: Ieccba6ecb16553ed5211f277b49e9f2ed2d7c745
diff --git a/src/com/android/launcher3/Launcher.java b/src/com/android/launcher3/Launcher.java
index 5da4944..5a1143fc 100644
--- a/src/com/android/launcher3/Launcher.java
+++ b/src/com/android/launcher3/Launcher.java
@@ -1193,6 +1193,12 @@
         }
     }
 
+    public void onQuickstepGestureStarted(boolean isVisible) {
+        if (mLauncherCallbacks != null) {
+            mLauncherCallbacks.onQuickstepGestureStarted(isVisible);
+        }
+    }
+
     public AllAppsTransitionController getAllAppsController() {
         return mAllAppsController;
     }
diff --git a/src/com/android/launcher3/LauncherCallbacks.java b/src/com/android/launcher3/LauncherCallbacks.java
index 914d9eb..ed7bf3d 100644
--- a/src/com/android/launcher3/LauncherCallbacks.java
+++ b/src/com/android/launcher3/LauncherCallbacks.java
@@ -71,4 +71,12 @@
      * Extensions points for adding / replacing some other aspects of the Launcher experience.
      */
     boolean hasSettings();
+
+    /**
+     * Called when launcher integrated quickstep and some quickstep gesture started. It can be
+     * called multiple times for a single gesture an UI or background thread.
+     *
+     * @param isVisible if Launcher was visible when the gesture started.
+     */
+    void onQuickstepGestureStarted(boolean isVisible);
 }