Do IWYU for public/fpdf_fwlevent.h.

Change-Id: Id45ea6185f7ccdf9f8aef4c6b0adc58dcd1dceb1
Reviewed-on: https://pdfium-review.googlesource.com/c/47151
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/fpdfsdk/cpdfsdk_annothandlermgr.cpp b/fpdfsdk/cpdfsdk_annothandlermgr.cpp
index 7d253c8..619d66d 100644
--- a/fpdfsdk/cpdfsdk_annothandlermgr.cpp
+++ b/fpdfsdk/cpdfsdk_annothandlermgr.cpp
@@ -17,6 +17,7 @@
 #include "fpdfsdk/cpdfsdk_pageview.h"
 #include "fpdfsdk/cpdfsdk_widget.h"
 #include "fpdfsdk/cpdfsdk_widgethandler.h"
+#include "public/fpdf_fwlevent.h"
 #include "third_party/base/ptr_util.h"
 
 #ifdef PDF_ENABLE_XFA