Add second copy request after screen rotation to flatten the layers in animation.

chrome/browser/flag_descriptions.h

Index: chrome/browser/flag_descriptions.h
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index c11429fd5fe19002ab3842687db5cf1af9cc725a..5281bde5f4ec9cae6e625d01b80fdd312f5fec78 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -786,6 +786,13 @@ extern const char kAshEnableMirroredScreenName[];
 // Description for the flag to enable the mirrored screen mode.
 extern const char kAshEnableMirroredScreenDescription[];
 
+// Title for the flag to enable the smoother screen rotation animation mode.
+extern const char kAshEnableSmoothScreenRotationName[];
+
+// Description for the flag to enable the smoother screen rotation animation
+// mode.
+extern const char kAshEnableSmoothScreenRotationDescription[];
+
 // Description for the flag that sets material design ink drop animation speed
 // of fast.
 extern const char kMaterialDesignInkDropAnimationFast[];