Invalidate IPWL_FocusHandler and IPWL_Provider on destruction.

fpdfsdk/src/fpdfview_embeddertest.cpp

Index: fpdfsdk/src/fpdfview_embeddertest.cpp
diff --git a/fpdfsdk/src/fpdfview_embeddertest.cpp b/fpdfsdk/src/fpdfview_embeddertest.cpp
index 0f4666836f50c83ce5d2d8811332a21a3de4bbbb..6eb5fb95cdbc25f2a9aebe5f480af1718cab0c42 100644
--- a/fpdfsdk/src/fpdfview_embeddertest.cpp
+++ b/fpdfsdk/src/fpdfview_embeddertest.cpp
@@ -196,10 +196,14 @@ TEST_F(FPDFViewEmbeddertest, Crasher_452455) {
 }
 
 TEST_F(FPDFViewEmbeddertest, Crasher_454695) {
-  // Document is damanged and can't be opened.
+  // Document is damaged and can't be opened.
   EXPECT_FALSE(OpenDocument("bug_454695.pdf"));
 }
 
+TEST_F(FPDFViewEmbeddertest, Crasher_572871) {
+  EXPECT_TRUE(OpenDocument("bug_572871.pdf"));
+}
+
 // The following tests pass if the document opens without infinite looping.
 TEST_F(FPDFViewEmbeddertest, Hang_298) {
   EXPECT_FALSE(OpenDocument("bug_298.pdf"));