Cancel the existing recents animation before any initialization

- In the rare case that we are canceling the recents animation as a
  part of starting another recents animation, ensure that we do it
  before we move the target activity to be visible, otherwise the
  cancelation will undo the previous work.

Bug: 193851085
Test: atest RecentsAnimationControllerTest
Change-Id: I22589a034eab3b1fab10f4b677f777b282305bbd

services/core/java/com/android/server/wm/RecentsAnimation.java

@@ -170,6 +170,13 @@ class RecentsAnimation implements RecentsAnimationCallbacks, OnRootTaskOrderChan
         ProtoLog.d(WM_DEBUG_RECENTS_ANIMATIONS, "startRecentsActivity(): intent=%s", mTargetIntent);
         Trace.traceBegin(TRACE_TAG_WINDOW_MANAGER, "RecentsAnimation#startRecentsActivity");
 
+        // Cancel any existing recents animation running synchronously (do not hold the
+        // WM lock) before starting the newly requested recents animation as they can not coexist
+        if (mWindowManager.getRecentsAnimationController() != null) {
+            mWindowManager.getRecentsAnimationController().forceCancelAnimation(
+                    REORDER_MOVE_TO_ORIGINAL_POSITION, "startRecentsActivity");
+        }
+
         // If the activity is associated with the root recents task, then try and get that first
         Task targetRootTask = mDefaultTaskDisplayArea.getRootTask(WINDOWING_MODE_UNDEFINED,
                 mTargetActivityType);
@@ -243,12 +250,7 @@ class RecentsAnimation implements RecentsAnimationCallbacks, OnRootTaskOrderChan
             targetActivity.intent.replaceExtras(mTargetIntent);
 
             // Fetch all the surface controls and pass them to the client to get the animation
-            // started. Cancel any existing recents animation running synchronously (do not hold the
-            // WM lock)
-            if (mWindowManager.getRecentsAnimationController() != null) {
-                mWindowManager.getRecentsAnimationController().forceCancelAnimation(
-                        REORDER_MOVE_TO_ORIGINAL_POSITION, "startRecentsActivity");
-            }
+            // started
             mWindowManager.initializeRecentsAnimation(mTargetActivityType, recentsAnimationRunner,
                     this, mDefaultTaskDisplayArea.getDisplayId(),
                     mTaskSupervisor.mRecentTasks.getRecentTaskIds(), targetActivity);