Fix nits from earlier CLs

pdf/pdfium/pdfium_engine.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/pdfium/pdfium_engine.h"
 
 #include <math.h>
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 1426 matching lines @@
                                      kPointsPerInch);
   double ratio_y = ConvertUnitDouble(bitmap_size.height(),
                                      print_settings.dpi,
                                      kPointsPerInch);
 
   // Add the bitmap to an image object and add the image object to the output
   // page.
   FPDF_PAGEOBJECT temp_img = FPDFPageObj_NewImgeObj(temp_doc);
 
   std::vector<uint8_t> compressed_bitmap_data;
-  int quality = 40;
+  // Use quality = 40 as this does not significantly degrade the printed
+  // document relative to a normal bitmap and provides better compression than
+  // a higher quality setting.
+  const int quality = 40;
   if (!(print_settings.format & PP_PRINTOUTPUTFORMAT_PDF) &&
       (gfx::JPEGCodec::Encode(
           bitmap_data, gfx::JPEGCodec::FORMAT_BGRA, FPDFBitmap_GetWidth(bitmap),
           FPDFBitmap_GetHeight(bitmap), FPDFBitmap_GetStride(bitmap), quality,
           &compressed_bitmap_data))) {
     FPDF_FILEACCESS file_access = {};
     file_access.m_FileLen =
         static_cast<unsigned long>(compressed_bitmap_data.size());
     file_access.m_GetBlock = &GetBlockForJpeg;
     file_access.m_Param = &compressed_bitmap_data;
@@ skipping 2738 matching lines @@
   FPDF_DOCUMENT doc =
       FPDF_LoadMemDocument(pdf_buffer, pdf_buffer_size, nullptr);
   if (!doc)
     return false;
   bool success = FPDF_GetPageSizeByIndex(doc, page_number, width, height) != 0;
   FPDF_CloseDocument(doc);
   return success;
 }
 
 }  // namespace chrome_pdf