Revert of 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 4bb62b3117d9e8fca2fc78ad6a2189e7dfc24c11..49eebdf5cea473b9155a7fda8c1be12fa84f56a2 100644
--- a/pdf/pdf_engine.h
+++ b/pdf/pdf_engine.h
@@ -186,9 +186,6 @@ class PDFEngine {
     // Get the background color of the PDF.
     virtual uint32_t GetBackgroundColor() = 0;
 
-    // Cancel browser initiated document download.
-    virtual void CancelBrowserDownload() = 0;
-
     // Sets selection status.
     virtual void IsSelectingChanged(bool is_selecting) {}
   };
@@ -301,6 +298,8 @@ class PDFEngine {
   virtual void SetScrollPosition(const pp::Point& position) = 0;
 #endif
 
+  virtual bool IsProgressiveLoad() = 0;
+
   virtual std::string GetMetadata(const std::string& key) = 0;
 };