Remove pageview from map immediately

fpdfsdk/fsdk_mgr.cpp

Index: fpdfsdk/fsdk_mgr.cpp
diff --git a/fpdfsdk/fsdk_mgr.cpp b/fpdfsdk/fsdk_mgr.cpp
index 68143d2bdde1df3a7ee808ee4d3fed6f0af0d3a7..d1e55074f9d07344f650b4dd225e96e3b1c324c2 100644
--- a/fpdfsdk/fsdk_mgr.cpp
+++ b/fpdfsdk/fsdk_mgr.cpp
@@ -353,9 +353,12 @@ void CPDFSDK_Document::RemovePageView(UnderlyingPageType* pUnderlyingPage) {
   if (pPageView->IsLocked())
     return;
 
+  // Remove the page from the map to make sure we don't accidentally attempt
+  // to use the |pPageView| while we're cleaning it up.
+  m_pageMap.erase(it);
+
   pPageView->KillFocusAnnotIfNeeded();
   delete pPageView;
-  m_pageMap.erase(it);
 }
 
 UnderlyingPageType* CPDFSDK_Document::GetPage(int nIndex) {