M52: PDF: Always call FPDFAvail_IsDocAvail() when loading.

BUG=613704

Review-Url: https://codereview.chromium.org/2006793003
Cr-Commit-Position: refs/heads/master@{#400286}
(cherry picked from commit 0968faa)

Review URL: https://codereview.chromium.org/2080313003 .

Cr-Commit-Position: refs/branch-heads/2743@{#406}
Cr-Branched-From: 2b3ae3b-refs/heads/master@{#394939}

pdf/pdfium/pdfium_engine.cc

@@ -298,7 +298,7 @@ FPDF_SYSFONTINFO g_font_info = {
 };
 #endif  // defined(OS_LINUX)
 
-PDFiumEngine* g_engine_for_unsupported;
+PDFiumEngine* g_engine_for_unsupported = nullptr;
 
 void Unsupported_Handler(UNSUPPORT_INFO*, int type) {
   if (!g_engine_for_unsupported) {
@@ -1049,6 +1049,7 @@ void PDFiumEngine::OnPartialDocumentLoaded() {
 
 void PDFiumEngine::OnPendingRequestComplete() {
   if (!doc_ || !form_) {
+    DCHECK(fpdf_availability_);
     LoadDocument();
     return;
   }
@@ -2417,8 +2418,13 @@ bool PDFiumEngine::TryLoadingDoc(bool with_password,
                                  const std::string& password,
                                  bool* needs_password) {
   *needs_password = false;
-  if (doc_)
+  if (doc_) {
+    // This is probably not necessary, because it should have already been
+    // called below in the |doc_| initialization path. However, the previous
+    // call may have failed, so call it again for good measure.
+    FPDFAvail_IsDocAvail(fpdf_availability_, &download_hints_);
     return true;
+  }
 
   const char* password_cstr = nullptr;
   if (with_password) {
@@ -2431,11 +2437,16 @@ bool PDFiumEngine::TryLoadingDoc(bool with_password,
   } else {
     doc_ = FPDFAvail_GetDocument(fpdf_availability_, password_cstr);
   }
+  if (!doc_) {
+    if (FPDF_GetLastError() == FPDF_ERR_PASSWORD)
+      *needs_password = true;
+    return false;
+  }
 
-  if (!doc_ && FPDF_GetLastError() == FPDF_ERR_PASSWORD)
-    *needs_password = true;
-
-  return !!doc_;
+  // Always call FPDFAvail_IsDocAvail() so PDFium initializes internal data
+  // structures.
+  FPDFAvail_IsDocAvail(fpdf_availability_, &download_hints_);
+  return true;
 }
 
 void PDFiumEngine::GetPasswordAndLoad() {

pdf/pdfium/pdfium_engine.h

@@ -212,7 +212,7 @@ class PDFiumEngine : public PDFEngine,
                      const std::string& password,
                      bool* needs_password);
 
-  // Ask the user for the document password and then continue loading the
+  // Asks the user for the document password and then continue loading the
   // document.
   void GetPasswordAndLoad();
 
@@ -225,17 +225,19 @@ class PDFiumEngine : public PDFEngine,
   void ContinueLoadingDocument(bool has_password,
                                const std::string& password);
 
-  // Finish loading the document and notify the client that the document has
-  // been loaded. This should only be run after |doc_| has been loaded and the
-  // document is fully downloaded. If this has been run once, it will result in
-  // a no-op.
+  // Finishes loading the document. Recalculate the document size if there were
+  // pages that were not previously available.
+  // Also notifies the client that the document has been loaded.
+  // This should only be called after |doc_| has been loaded and the document is
+  // fully downloaded.
+  // If this has been run once, it will not notify the client again.
   void FinishLoadingDocument();
 
   // Loads information about the pages in the document and calculate the
   // document size.
   void LoadPageInfo(bool reload);
 
-  // Calculate which pages should be displayed right now.
+  // Calculates which pages should be displayed right now.
   void CalculateVisiblePages();
 
   // Returns true iff the given page index is visible.  CalculateVisiblePages