Guard against double deletion of page views.

This CL adds a |IsBeingDestroyed| flag into the CPDFSDK_PageView. We then
bail out of the pageview removal code early if the flag is set.

BUG=chromium:652103

Review-Url: https://codereview.chromium.org/2384243002

fpdfsdk/cpdfsdk_document.cpp

diff --git a/fpdfsdk/cpdfsdk_document.cpp b/fpdfsdk/cpdfsdk_document.cpp
index ad4516d..66851c0 100644
--- a/fpdfsdk/cpdfsdk_document.cpp
+++ b/fpdfsdk/cpdfsdk_document.cpp
@@ -135,9 +135,13 @@
     return;
 
   CPDFSDK_PageView* pPageView = it->second;
-  if (pPageView->IsLocked())
+  if (pPageView->IsLocked() || pPageView->IsBeingDestroyed())
     return;
 
+  // Mark the page view so we do not come into |RemovePageView| a second
+  // time while we're in the process of removing.
+  pPageView->SetBeingDestroyed();
+
   // This must happen before we remove |pPageView| from the map because
   // |KillFocusAnnotIfNeeded| can call into the |GetPage| method which will
   // look for this page view in the map, if it doesn't find it a new one will

fpdfsdk/cpdfsdk_pageview.cpp

diff --git a/fpdfsdk/cpdfsdk_pageview.cpp b/fpdfsdk/cpdfsdk_pageview.cpp
index beba7b6..2e7e6c0 100644
--- a/fpdfsdk/cpdfsdk_pageview.cpp
+++ b/fpdfsdk/cpdfsdk_pageview.cpp
@@ -39,7 +39,8 @@
       m_bExitWidget(FALSE),
       m_bOnWidget(FALSE),
       m_bValid(FALSE),
-      m_bLocked(FALSE) {
+      m_bLocked(FALSE),
+      m_bBeingDestroyed(false) {
   CPDFSDK_InterForm* pInterForm = pSDKDoc->GetInterForm();
   if (pInterForm) {
     CPDF_InterForm* pPDFInterForm = pInterForm->GetInterForm();

fpdfsdk/cpdfsdk_pageview.h

diff --git a/fpdfsdk/cpdfsdk_pageview.h b/fpdfsdk/cpdfsdk_pageview.h
index fe40300..f837ba5 100644
--- a/fpdfsdk/cpdfsdk_pageview.h
+++ b/fpdfsdk/cpdfsdk_pageview.h
@@ -98,6 +98,10 @@
 
   void SetLock(FX_BOOL bLocked) { m_bLocked = bLocked; }
   FX_BOOL IsLocked() { return m_bLocked; }
+
+  void SetBeingDestroyed() { m_bBeingDestroyed = true; }
+  bool IsBeingDestroyed() const { return m_bBeingDestroyed; }
+
 #ifndef PDF_ENABLE_XFA
   bool OwnsPage() const { return m_bOwnsPage; }
   void TakePageOwnership() { m_bOwnsPage = true; }
@@ -120,6 +124,7 @@
   FX_BOOL m_bOnWidget;
   FX_BOOL m_bValid;
   FX_BOOL m_bLocked;
+  bool m_bBeingDestroyed;
 };
 
 #endif  // FPDFSDK_CPDFSDK_PAGEVIEW_H_

fpdfsdk/fpdfview.cpp

diff --git a/fpdfsdk/fpdfview.cpp b/fpdfsdk/fpdfview.cpp
index 5c5532e..e48c2e9 100644
--- a/fpdfsdk/fpdfview.cpp
+++ b/fpdfsdk/fpdfview.cpp
@@ -670,6 +670,10 @@
   CPDFSDK_PageView* pPageView =
       static_cast<CPDFSDK_PageView*>(pPage->GetView());
   if (pPageView) {
+    // We're already destroying the pageview, so bail early.
+    if (pPageView->IsBeingDestroyed())
+      return;
+
     if (pPageView->IsLocked()) {
       pPageView->TakePageOwnership();
       return;