Printing: Fix undefined behavior for near 0 scaling

components/printing/renderer/print_web_view_helper_mac.mm

 // 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 "components/printing/renderer/print_web_view_helper.h"
 
 #import <AppKit/AppKit.h>
 
 #include "base/logging.h"
 #include "base/mac/scoped_nsautorelease_pool.h"
@@ skipping 96 matching lines @@
 }
 #endif  // defined(ENABLE_PRINT_PREVIEW)
 
 void PrintWebViewHelper::RenderPage(const PrintMsg_Print_Params& params,
                                     int page_number,
                                     blink::WebLocalFrame* frame,
                                     bool is_preview,
                                     PdfMetafileSkia* metafile,
                                     gfx::Size* page_size,
                                     gfx::Rect* content_rect) {
-  double scale_factor = params.scale_factor > 0 ? params.scale_factor : 1.0f;
+  double scale_factor =
+      params.scale_factor >= kEpsilon ? params.scale_factor : 1.0f;
   double webkit_shrink_factor = frame->getPrintPageShrink(page_number);
   PageSizeMargins page_layout_in_points;
   gfx::Rect content_area;
 
   ComputePageLayoutInPointsForCss(frame, page_number, params,
                                   ignore_css_margins_, &scale_factor,
                                   &page_layout_in_points);
   GetPageSizeAndContentAreaFromPageLayout(page_layout_in_points, page_size,
                                           &content_area);
   if (content_rect)
@@ skipping 22 matching lines @@
 #endif  // defined(ENABLE_PRINT_PREVIEW)
     RenderPageContent(frame, page_number, canvas_area, content_area,
                       scale_factor, static_cast<blink::WebCanvas*>(canvas));
   }
 
   // Done printing. Close the device context to retrieve the compiled metafile.
   metafile->FinishPage();
 }
 
 }  // namespace printing