Fixup page removal for XFA documents.

fpdfsdk/fpdfdoc_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 <string>
 
 #include "core/fxcrt/include/fx_string.h"
 #include "public/fpdf_doc.h"
+#include "public/fpdf_edit.h"
 #include "public/fpdfview.h"
 #include "testing/embedder_test.h"
 #include "testing/fx_string_testhelpers.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/test_support.h"
 
 class FPDFDocEmbeddertest : public EmbedderTest {};
 
 TEST_F(FPDFDocEmbeddertest, DestGetPageIndex) {
   EXPECT_TRUE(OpenDocument("named_dests.pdf"));
@@ skipping 112 matching lines @@
 // Check circular bookmarks will not cause infinite loop.
 TEST_F(FPDFDocEmbeddertest, FindBookmarks_bug420) {
   // Open a file with circular bookmarks.
   EXPECT_TRUE(OpenDocument("bookmarks_circular.pdf"));
 
   // Try to find a title.
   std::unique_ptr<unsigned short, pdfium::FreeDeleter> title =
       GetFPDFWideString(L"anything");
   EXPECT_EQ(nullptr, FPDFBookmark_Find(document(), title.get()));
 }
+
+TEST_F(FPDFDocEmbeddertest, DeletePage) {
+  EXPECT_TRUE(OpenDocument("hello_world.pdf"));
+  EXPECT_EQ(1, FPDF_GetPageCount(document()));
+  FPDFPage_Delete(document(), 0);
+  EXPECT_EQ(0, FPDF_GetPageCount(document()));
+}