DO NOT MERGE Revert "DO NOT MERGE Revert "Handle dream restart""

This reverts commit 36acacd2a0.

Reason for revert: reland this with fix for b/270178573

Fix: 265110360
Fix: 260205205

Change-Id: I0eaa29021b4f8ffeb572877e5ecefbf5f1b4dd18

services/core/java/com/android/server/dreams/DreamController.java

@@ -42,6 +42,7 @@ import java.io.PrintWriter;
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
+import java.util.Objects;
 
 /**
  * Internal controller for starting and stopping the current dream and managing related state.
@@ -119,10 +120,20 @@ final class DreamController {
                     + ", isPreviewMode=" + isPreviewMode + ", canDoze=" + canDoze
                     + ", userId=" + userId + ", reason='" + reason + "'");
 
-            if (mCurrentDream != null) {
-                mPreviousDreams.add(mCurrentDream);
-            }
+            final DreamRecord oldDream = mCurrentDream;
             mCurrentDream = new DreamRecord(token, name, isPreviewMode, canDoze, userId, wakeLock);
+            if (oldDream != null) {
+                if (!oldDream.mWakingGently) {
+                    // We will stop these previous dreams once the new dream is started.
+                    mPreviousDreams.add(oldDream);
+                } else if (Objects.equals(oldDream.mName, mCurrentDream.mName)) {
+                    // We are attempting to start a dream that is currently waking up gently.
+                    // Let's silently stop the old instance here to clear the dream state.
+                    // This should happen after the new mCurrentDream is set to avoid announcing
+                    // a "dream stopped" state.
+                    stopDreamInstance(/* immediately */ true, "restarting same dream", oldDream);
+                }
+            }
 
             mCurrentDream.mDreamStartTime = SystemClock.elapsedRealtime();
             MetricsLogger.visible(mContext,