Add FPDF_ANNOT in PDFiumEngine::GetRenderingFlags.

This is a preparation CL for implementing toggle annotation button.

FPDF_ANNOT flag is needed to draw non-widget type PDF annotations, such
as text, highlight, underline, etc. Same flag needs to be passed to
FPDF_RenderPageBitmap_Start and FPDF_FFLDraw in order to display /
hide popup window associated to non-widget annotation on mouse-hover.

BUG=642982

Review-Url: https://codereview.chromium.org/2328893002
Cr-Commit-Position: refs/heads/master@{#417745}

pdf/pdfium/pdfium_engine.cc

@@ -551,6 +551,7 @@ PDFiumEngine::PDFiumEngine(PDFEngine::Client* client)
       most_visible_page_(-1),
       called_do_document_action_(false),
       render_grayscale_(false),
+      render_annots_(true),
       progressive_paint_timeout_(0),
       getting_password_(false) {
   find_factory_.Initialize(this);
@@ -2986,6 +2987,8 @@ int PDFiumEngine::GetRenderingFlags() const {
     flags |= FPDF_GRAYSCALE;
   if (client_->IsPrintPreview())
     flags |= FPDF_PRINTING;
+  if (render_annots_)
+    flags |= FPDF_ANNOT;
   return flags;
 }
 

pdf/pdfium/pdfium_engine.h

@@ -699,6 +699,9 @@ class PDFiumEngine : public PDFEngine,
   // Whether to render in grayscale or in color.
   bool render_grayscale_;
 
+  // Whether to render PDF annotations.
+  bool render_annots_;
+
   // The link currently under the cursor.
   std::string link_under_cursor_;