Improve linearized pdf load/show time.

pdf/pdf_engine.h

Index: pdf/pdf_engine.h
diff --git a/pdf/pdf_engine.h b/pdf/pdf_engine.h
index 4d17a403b184ebfa856c76a384a5f9de49319e6f..fec99128b9651bc6d60291f189f37ac4893a2669 100644
--- a/pdf/pdf_engine.h
+++ b/pdf/pdf_engine.h
@@ -183,6 +183,8 @@ class PDFEngine {
     // Get the background color of the PDF.
     virtual uint32_t GetBackgroundColor() = 0;
 
+    virtual void CancelBrowserDownload() = 0;
+
     // Sets selection status.
     virtual void IsSelectingChanged(bool is_selecting) {}
   };
@@ -295,8 +297,6 @@ class PDFEngine {
   virtual void SetScrollPosition(const pp::Point& position) = 0;
 #endif
 
-  virtual bool IsProgressiveLoad() = 0;
-
   virtual std::string GetMetadata(const std::string& key) = 0;
 };