Export a function from the PDF plugin to get the dimensions of a PDF page.

pdf/pdf_engine.h

Index: pdf/pdf_engine.h
diff --git a/pdf/pdf_engine.h b/pdf/pdf_engine.h
index ee1cb1ff000341f1f0569dc1d617de11ee1260f5..394791739195ecc3a8f4ce49b3028496fc21769c 100644
--- a/pdf/pdf_engine.h
+++ b/pdf/pdf_engine.h
@@ -312,6 +312,10 @@ class PDFEngineExports {
                              int buffer_size,
                              int* page_count,
                              double* max_page_width) = 0;
+
+  virtual bool GetPDFPageSizeByIndex(const void* pdf_buffer,
+                                     int buffer_size, int index,
+                                     double* width, double* height) = 0;
 };
 
 }  // namespace chrome_pdf