Do more page load/unload checks in EmbedderTest.

- Keep track of pages in a single map when calling LoadPage(). It is
  simpler and performance is not crucial as the number of loaded pages
  is usually very small.
- Verify UnloadPage() is only called for loaded pages.
- Verify there are no loaded pages in TearDown().
- Verify RenderLoadedPage methods are only rendering loaded pages.
- Fix pages that are using FPDF_LoadPage() and FPDF_ClosePage() when
  they should be using LoadPage() and UnloadPage().
- Disallow calling LoadPage() for the same page number repeatedly. No
  caller does this and it makes verification in UnloadPage() harder.

Change-Id: I58878ea8ade21dde28f1bbebd3a3304ce677561d
Reviewed-on: https://pdfium-review.googlesource.com/25550
Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>

1 files changed, 13 insertions, 4 deletions

diff --git a/testing/embedder_test.h b/testing/embedder_test.h
index 18b16b7066..c8fce4825f 100644
--- a/testing/embedder_test.h
+++ b/testing/embedder_test.h
@@ -106,11 +106,17 @@ class EmbedderTest : public ::testing::Test,
   int GetFirstPageNum();
   int GetPageCount();
 
-  // Load a specific page of the open document.
+  // Load a specific page of the open document with a given non-negative
+  // |page_number|. On success, fire form events for the page and return a page
+  // handle. On failure, return nullptr.
+  // The caller does not own the returned page handle, but must call
+  // UnloadPage() on it when done.
+  // The caller cannot call this for a |page_number| if it already obtained and
+  // holds the page handle for that page.
   FPDF_PAGE LoadPage(int page_number);
 
-  // Release the resources obtained from LoadPage(). Further use of |page|
-  // is prohibited after this call is made.
+  // Fire form unload events and release the resources for a |page| obtained
+  // from LoadPage(). Further use of |page| is prohibited after calling this.
   void UnloadPage(FPDF_PAGE page);
 
   // Convert a loaded page into a bitmap.
@@ -215,7 +221,6 @@ class EmbedderTest : public ::testing::Test,
   size_t file_length_ = 0;
   std::unique_ptr<char, pdfium::FreeDeleter> file_contents_;
   std::map<int, FPDF_PAGE> page_map_;
-  std::map<FPDF_PAGE, int> page_reverse_map_;
 
   FPDF_DOCUMENT saved_document_ = nullptr;
   FPDF_FORMHANDLE saved_form_handle_ = nullptr;
@@ -242,6 +247,10 @@ class EmbedderTest : public ::testing::Test,
                                 const void* data,
                                 unsigned long size);
 
+  // Find |page| inside |page_map_| and return the associated page number, or -1
+  // if |page| cannot be found.
+  int GetPageNumberForLoadedPage(FPDF_PAGE page) const;
+
   std::string data_string_;
 };