PDF rotation should maintain current page.

pdf/pdf_engine.h

 // 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.
 
 #ifndef PDF_PDF_ENGINE_H_
 #define PDF_PDF_ENGINE_H_
 
 #include <stdint.h>
 
 #include "build/build_config.h"
@@ skipping 53 matching lines @@
     // Informs the client that the given rect needs to be repainted.
     virtual void Invalidate(const pp::Rect& rect) = 0;
 
     // Informs the client to scroll the plugin area by the given offset.
     virtual void Scroll(const pp::Point& point) = 0;
 
     // Scroll the horizontal/vertical scrollbars to a given position.
     virtual void ScrollToX(int position) = 0;
     virtual void ScrollToY(int position) = 0;
 
-    // Scroll to the specified page.
+    // Scroll to zero-based |page|.
     virtual void ScrollToPage(int page) = 0;
 
     // Navigate to the given url.
     virtual void NavigateTo(const std::string& url,
                             WindowOpenDisposition disposition) = 0;
 
     // Updates the cursor.
     virtual void UpdateCursor(PP_CursorType_Dev cursor) = 0;
 
     // Updates the tick marks in the vertical scrollbar.
@@ skipping 255 matching lines @@
 
   // See the definition of GetPDFPageSizeByIndex in pdf.cc for details.
   virtual bool GetPDFPageSizeByIndex(const void* pdf_buffer,
                                      int pdf_buffer_size, int page_number,
                                      double* width, double* height) = 0;
 };
 
 }  // namespace chrome_pdf
 
 #endif  // PDF_PDF_ENGINE_H_