Fix flushing issue in DefaultVideoFrameProcessor

Before this CL, the following scenario could happen:
- A new input stream is registered to the DefaultVideoFrameProcessor.
- Before the pipeline is reconfigured, a seek is issued andd the
  DefaultVideoFrameProcessor is flushed.
- As a result, the new input stream registration is never taken into
  account.

As a result:
- If an input stream is registered after the seek (before queueing any
  frame), registerInputStream will block indefinitely because
  inputStreamRegisteredCondition will be closed.
- If a frame is queued after the seek, it will be linked to the input
  stream information of the previous frames.

This CL makes sure that any pending input stream is registered after a
flush.

PiperOrigin-RevId: 698736866

libraries/effect/src/main/java/androidx/media3/effect/DefaultVideoFrameProcessor.java

@@ -516,14 +516,7 @@ public final class DefaultVideoFrameProcessor implements VideoFrameProcessor {
             listenerExecutor.execute(listener::onEnded);
             DebugTraceUtil.logEvent(COMPONENT_VFP, EVENT_SIGNAL_ENDED, C.TIME_END_OF_SOURCE);
           } else {
-            synchronized (lock) {
-              if (pendingInputStreamInfo != null) {
-                InputStreamInfo pendingInputStreamInfo = this.pendingInputStreamInfo;
-                videoFrameProcessingTaskExecutor.submit(
-                    () -> configure(pendingInputStreamInfo, /* forceReconfigure= */ false));
-                this.pendingInputStreamInfo = null;
-              }
-            }
+            submitPendingInputStream();
           }
         });
   }
@@ -762,6 +755,8 @@ public final class DefaultVideoFrameProcessor implements VideoFrameProcessor {
     } catch (InterruptedException e) {
       Thread.currentThread().interrupt();
     }
+    // Make sure any pending input stream is not swallowed.
+    submitPendingInputStream();
   }
 
   @Override
@@ -796,6 +791,17 @@ public final class DefaultVideoFrameProcessor implements VideoFrameProcessor {
     }
   }
 
+  private void submitPendingInputStream() {
+    synchronized (lock) {
+      if (pendingInputStreamInfo != null) {
+        InputStreamInfo pendingInputStreamInfo = this.pendingInputStreamInfo;
+        videoFrameProcessingTaskExecutor.submit(
+            () -> configure(pendingInputStreamInfo, /* forceReconfigure= */ false));
+        this.pendingInputStreamInfo = null;
+      }
+    }
+  }
+
   // Methods that must be called on the GL thread.
 
   /**