Fixup FPDFAvail_IsPageAvail checks in PDFiumEngine.

pdf/pdfium/pdfium_engine.cc

Index: pdf/pdfium/pdfium_engine.cc
diff --git a/pdf/pdfium/pdfium_engine.cc b/pdf/pdfium/pdfium_engine.cc
index 5ee7e623ac43e20b3098cb3097ff2bec45443f99..84943f71dd0a5537b212ed67ce643afd8c9d5d04 100644
--- a/pdf/pdfium/pdfium_engine.cc
+++ b/pdf/pdfium/pdfium_engine.cc
@@ -1099,7 +1099,13 @@ void PDFiumEngine::FinishLoadingDocument() {
     pages_[i]->set_available(true);
     // We still need to call IsPageAvail() even if the whole document is
     // already downloaded.
-    FPDFAvail_IsPageAvail(fpdf_availability_, i, &download_hints_);
+    while (true) {

[dsinclair, 2016/06/02 18:03:25]

This is probably bad, and I feel bad, but I wasn't sure the correct solution
....

+      int val = FPDFAvail_IsPageAvail(fpdf_availability_, i, &download_hints_);
+      if (val == PDF_DATA_ERROR)
+        return;
+      if (val == PDF_DATA_AVAIL)
+        break;
+    }
     need_update = true;
     if (IsPageVisible(i))
       client_->Invalidate(GetPageScreenRect(i));
@@ -2634,7 +2640,8 @@ bool PDFiumEngine::CheckPageAvailable(int index, std::vector<int>* pending) {
   if (index < num_pages && pages_[index]->available())
     return true;
 
-  if (!FPDFAvail_IsPageAvail(fpdf_availability_, index, &download_hints_)) {
+  if (FPDFAvail_IsPageAvail(fpdf_availability_, index, &download_hints_) !=
+      PDF_DATA_AVAIL) {
     if (!ContainsValue(*pending, index))
       pending->push_back(index);
     return false;