Revert of Remove some dead PDF code.

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 3f0b3120edb65b161a2c9aa9c7d0c0151fe831ab..6506d8c96b1038af85ffed479c6b7d05e9dcb8c1 100644
--- a/pdf/pdfium/pdfium_engine.cc
+++ b/pdf/pdfium/pdfium_engine.cc
@@ -527,6 +527,7 @@
       fpdf_availability_(NULL),
       next_timer_id_(0),
       last_page_mouse_down_(-1),
+      first_visible_page_(-1),
       most_visible_page_(-1),
       called_do_document_action_(false),
       render_grayscale_(false),
@@ -2276,6 +2277,10 @@
   return url;
 }
 
+bool PDFiumEngine::IsSelecting() {
+  return selecting_;
+}
+
 bool PDFiumEngine::HasPermission(DocumentPermission permission) const {
   // PDF 1.7 spec, section 3.5.2 says: "If the revision number is 2 or greater,
   // the operations to which user access can be controlled are as follows: ..."
@@ -2345,6 +2350,11 @@
   return dest ? FPDFDest_GetPageIndex(doc_, dest) : -1;
 }
 
+int PDFiumEngine::GetFirstVisiblePage() {
+  CalculateVisiblePages();
+  return first_visible_page_;
+}
+
 int PDFiumEngine::GetMostVisiblePage() {
   CalculateVisiblePages();
   return most_visible_page_;
@@ -2359,6 +2369,26 @@
 
 pp::Rect PDFiumEngine::GetPageContentsRect(int index) {
   return GetScreenRect(pages_[index]->rect());
+}
+
+void PDFiumEngine::PaintThumbnail(pp::ImageData* image_data, int index) {
+  FPDF_BITMAP bitmap = FPDFBitmap_CreateEx(
+      image_data->size().width(), image_data->size().height(),
+      FPDFBitmap_BGRx, image_data->data(), image_data->stride());
+
+  if (pages_[index]->available()) {
+    FPDFBitmap_FillRect(bitmap, 0, 0, image_data->size().width(),
+                        image_data->size().height(), 0xFFFFFFFF);
+
+    FPDF_RenderPageBitmap(
+        bitmap, pages_[index]->GetPage(), 0, 0, image_data->size().width(),
+        image_data->size().height(), 0, GetRenderingFlags());
+  } else {
+    FPDFBitmap_FillRect(bitmap, 0, 0, image_data->size().width(),
+                        image_data->size().height(), kPendingPageColor);
+  }
+
+  FPDFBitmap_Destroy(bitmap);
 }
 
 void PDFiumEngine::SetGrayscale(bool grayscale) {
@@ -2689,10 +2719,15 @@
   // screen coordinates.
   form_highlights_.clear();
 
-  int most_visible_page = visible_pages_.empty() ? 0 : visible_pages_.front();
-  DCHECK_GE(most_visible_page, 0);
+  if (visible_pages_.size() == 0)
+    first_visible_page_ = -1;
+  else
+    first_visible_page_ = visible_pages_.front();
+
+  int most_visible_page = first_visible_page_;
   // Check if the next page is more visible than the first one.
-  if (!pages_.empty() &&
+  if (most_visible_page != -1 &&
+      pages_.size() > 0 &&
       most_visible_page < static_cast<int>(pages_.size()) - 1) {
     pp::Rect rc_first =
         visible_rect.Intersect(GetPageScreenRect(most_visible_page));