Merge to M45: Fix heap use after free in CPDFSDK_Annot::GetPDFAnnot.

fpdfsdk/src/fpdfformfill_embeddertest.cpp

 // Copyright 2015 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 
 #include "../../public/fpdf_formfill.h"
 #include "../../testing/embedder_test.h"
 #include "../../testing/embedder_test_mock_delegate.h"
 #include "../../testing/embedder_test_timer_handling_delegate.h"
 #include "testing/gmock/include/gmock/gmock.h"
@@ skipping 23 matching lines @@
   EmbedderTestTimerHandlingDelegate delegate;
   SetDelegate(&delegate);
 
   EXPECT_TRUE(OpenDocument("testing/resources/bug_487928.pdf"));
   FPDF_PAGE page = LoadPage(0);
   EXPECT_NE(nullptr, page);
   DoOpenActions();
   delegate.AdvanceTime(5000);
   UnloadPage(page);
 }
+
+TEST_F(FPDFFormFillEmbeddertest, BUG_507316) {
+  EmbedderTestTimerHandlingDelegate delegate;
+  SetDelegate(&delegate);
+
+  EXPECT_TRUE(OpenDocument("testing/resources/bug_507316.pdf"));
+  FPDF_PAGE page = LoadAndCachePage(2);
+  EXPECT_NE(nullptr, page);
+  DoOpenActions();
+  delegate.AdvanceTime(4000);
+  UnloadPage(page);
+}