Use an older version of SurfaceTexture.setOnFrameAvailableListener wh…

…en running on pre-Lollipop devices (flutter#6489)

Fixes flutter/flutter#21730

shell/platform/android/io/flutter/view/FlutterView.java

@@ -1041,24 +1041,33 @@ final class SurfaceTextureRegistryEntry implements TextureRegistry.SurfaceTextur
         SurfaceTextureRegistryEntry(long id, SurfaceTexture surfaceTexture) {
             this.id = id;
             this.surfaceTexture = surfaceTexture;
-            this.surfaceTexture.setOnFrameAvailableListener(new SurfaceTexture.OnFrameAvailableListener() {
-                @Override
-                public void onFrameAvailable(SurfaceTexture texture) {
-                    if (released) {
-                        // Even though we make sure to unregister the callback before releasing, as of Android O
-                        // SurfaceTexture has a data race when accessing the callback, so the callback may
-                        // still be called by a stale reference after released==true and mNativeView==null.
-                        return;
-                    }
-                    nativeMarkTextureFrameAvailable(mNativeView.get(), SurfaceTextureRegistryEntry.this.id);
-                }
-            },
-            // The callback relies on being executed on the UI thread (unsynchronised read of mNativeView
-            // and also the engine code check for platform thread in Shell::OnPlatformViewMarkTextureFrameAvailable),
-            // so we explicitly pass a Handler for the current thread.
-            new Handler());
+
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+                // The callback relies on being executed on the UI thread (unsynchronised read of mNativeView
+                // and also the engine code check for platform thread in Shell::OnPlatformViewMarkTextureFrameAvailable),
+                // so we explicitly pass a Handler for the current thread.
+                this.surfaceTexture.setOnFrameAvailableListener(onFrameListener, new Handler());
+            } else {
+                // Android documentation states that the listener can be called on an arbitrary thread.
+                // But in practice, versions of Android that predate the newer API will call the listener
+                // on the thread where the SurfaceTexture was constructed.
+                this.surfaceTexture.setOnFrameAvailableListener(onFrameListener);
+            }
         }
 
+        private SurfaceTexture.OnFrameAvailableListener onFrameListener = new SurfaceTexture.OnFrameAvailableListener() {
+            @Override
+            public void onFrameAvailable(SurfaceTexture texture) {
+                if (released) {
+                    // Even though we make sure to unregister the callback before releasing, as of Android O
+                    // SurfaceTexture has a data race when accessing the callback, so the callback may
+                    // still be called by a stale reference after released==true and mNativeView==null.
+                    return;
+                }
+                nativeMarkTextureFrameAvailable(mNativeView.get(), SurfaceTextureRegistryEntry.this.id);
+            }
+        };
+
         @Override
         public SurfaceTexture surfaceTexture() {
             return surfaceTexture;