Make CPDF_Page retainable.

Small step to reducing the differences between XFA and non-XFA. We
still use the RetainPtr pretty much as if it were an unique_ptr, in
that we're not yet caching pages and handing out multiple pointers
to the same page in the non-XFA case.

The one change is in page view cleanup, where we no longer need a
boolean and can take (sufficient) page ownership with a RetainPtr.

Tidy up some document.h -> page.h -> document.h circular inclusion
while we're at it.

NOTE: Wait for imminent branch to pass before landing. We'll want
this to bake a while.

Change-Id: I64a2f12ac3424ece1063d40583995b834117cf34
Reviewed-on: https://pdfium-review.googlesource.com/32790
Reviewed-by: dsinclair <dsinclair@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/fpdfsdk/fpdf_ppo.cpp b/fpdfsdk/fpdf_ppo.cpp
index 1790e17fb3..b73042466b 100644
--- a/fpdfsdk/fpdf_ppo.cpp
+++ b/fpdfsdk/fpdf_ppo.cpp
@@ -618,9 +618,9 @@ bool CPDF_NPageToOneExporter::ExportNPagesToOne(
       if (!pSrcPageDict)
         return false;
 
-      CPDF_Page srcPage(src(), pSrcPageDict, true);
+      auto srcPage = pdfium::MakeRetain<CPDF_Page>(src(), pSrcPageDict, true);
       NupPageSettings settings =
-          nupState.CalculateNewPagePosition(srcPage.GetPageSize());
+          nupState.CalculateNewPagePosition(srcPage->GetPageSize());
       AddSubPage(pSrcPageDict, settings, &objectNumberMap, &pageXObjectMap,
                  &xObjNameNumberMap, &bsContent);
     }