Let PDFium handle event when there is not yet a visible page.

pdf/instance.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "pdf/instance.h"
 
 #include <algorithm>  // for min()
 #define _USE_MATH_DEFINES  // for M_PI
 #include <cmath>      // for log() and pow()
 #include <math.h>
@@ skipping 502 matching lines @@
     bool page_up = no_h_scrollbar && key_code == ui::VKEY_LEFT;
     if (zoom_mode_ == ZOOM_FIT_TO_PAGE) {
       bool has_shift =
           keyboard_event.GetModifiers() & PP_INPUTEVENT_MODIFIER_SHIFTKEY;
       bool key_is_space = key_code == ui::VKEY_SPACE;
       page_down |= key_is_space || key_code == ui::VKEY_NEXT;
       page_up |= (key_is_space && has_shift) || (key_code == ui::VKEY_PRIOR);
     }
     if (page_down) {
       int page = engine_->GetFirstVisiblePage();
+      if (page == -1)
+        return true;
       // Engine calculates visible page including delimiter to the page size.
       // We need to check here if the page itself is completely out of view and
       // scroll to the next one in that case.
       if (engine_->GetPageRect(page).bottom() * zoom_ <=
           v_scrollbar_->GetValue())
         page++;
       ScrollToPage(page + 1);
       UpdateCursor(PP_CURSORTYPE_POINTER);
       return true;
     } else if (page_up) {
       int page = engine_->GetFirstVisiblePage();
+      if (page == -1)
+        return true;
       if (engine_->GetPageRect(page).y() * zoom_ >= v_scrollbar_->GetValue())
         page--;
       ScrollToPage(page);
       UpdateCursor(PP_CURSORTYPE_POINTER);
       return true;
     }
   }
 
   if (v_scrollbar_.get() && v_scrollbar_->HandleEvent(event)) {
     UpdateCursor(PP_CURSORTYPE_POINTER);
@@ skipping 2195 matching lines @@
   return instance_->HasScriptableMethod(name, exception);
 }
 
 pp::Var PDFScriptableObject::Call(const pp::Var& method,
                                   const std::vector<pp::Var>& args,
                                   pp::Var* exception) {
   return instance_->CallScriptableMethod(method, args, exception);
 }
 
 }  // namespace chrome_pdf