Add tests to exercise FPDF_SaveAsCopy().

testing/embedder_test.h

Index: testing/embedder_test.h
diff --git a/testing/embedder_test.h b/testing/embedder_test.h
index df2e40a2e823078f1e584cc6c3d82135fe6376bb..68ffbecff44a80c6b08bf20e4d30ebab9dc14eea 100644
--- a/testing/embedder_test.h
+++ b/testing/embedder_test.h
@@ -58,9 +58,25 @@ class EmbedderTest : public ::testing::Test,
     std::map<int, FPDF_PAGE> m_pageMap;
   };
 
+  struct LoadDocumentData {
+    FPDF_DOCUMENT* document;
+    FPDF_FILEACCESS* file_access;
+    FX_FILEAVAIL* file_avail;
+    FPDF_AVAIL* avail;
+    FX_DOWNLOADHINTS* hints;
+    FPDF_FORMHANDLE* form_handle;
+  };
+
   EmbedderTest();
   virtual ~EmbedderTest();
 
+  static bool LoadDocument(const char* data,
+                           size_t data_size,
+                           bool must_linearize,
+                           TestLoader* loader,
+                           EmbedderTest* embedder_test,
+                           LoadDocumentData* out_data);
+
   void SetUp() override;
   void TearDown() override;