Setting focus on a widget may destroy the widget

When a widget has focus set, this can trigger an Invalidation call which
can trigger a page and annotation reload. This reload can destroy the
current widget we're handling.

This CL adds ObservedPtrs as needed so we can make sure the widgets are
still alive after we've done the Invalidation.

Bug: chromium:765921
Change-Id: I51cd24aa1ebd96abe9478efef5130a4e568dac1a
Reviewed-on: https://pdfium-review.googlesource.com/14290
Commit-Queue: dsinclair <dsinclair@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>

1 files changed, 10 insertions, 2 deletions

diff --git a/fpdfsdk/pwl/cpwl_edit.cpp b/fpdfsdk/pwl/cpwl_edit.cpp
index c71dbe4be0..0b74a1896e 100644
--- a/fpdfsdk/pwl/cpwl_edit.cpp
+++ b/fpdfsdk/pwl/cpwl_edit.cpp
@@ -331,16 +331,24 @@ bool CPWL_Edit::OnRButtonUp(const CFX_PointF& point, uint32_t nFlag) {
 }
 
 void CPWL_Edit::OnSetFocus() {
+  ObservedPtr observed_ptr(this);
   SetEditCaret(true);
+  if (!observed_ptr)
+    return;
+
   if (!IsReadOnly()) {
-    if (CPWL_Wnd::FocusHandlerIface* pFocusHandler = GetFocusHandler())
+    if (CPWL_Wnd::FocusHandlerIface* pFocusHandler = GetFocusHandler()) {
       pFocusHandler->OnSetFocus(this);
+      if (!observed_ptr)
+        return;
+    }
   }
   m_bFocus = true;
 }
 
 void CPWL_Edit::OnKillFocus() {
-  ObservedPtr observed_ptr = ObservedPtr(this);
+  ObservedPtr observed_ptr(this);
+
   CPWL_ScrollBar* pScroll = GetVScrollBar();
   if (pScroll && pScroll->IsVisible()) {
     pScroll->SetVisible(false);