Use paint recording scale factor instead of device scale factor

The paint recording scale factor is set to 1 when pixel canvas is
disabled. We cannot use the value of PaintContext::device_scale_factor
for the recording scale factor in such cases.

Bug: 813463
Change-Id: If51bfde2e271ce863cf3971016ee6347cbce592a
Component: Tabs, Clipping, Scaling
Reviewed-on: https://chromium-review.googlesource.com/927182Reviewed-by: Peter Kasting <pkasting@chromium.org>
Commit-Queue: Malay Keshav <malaykeshav@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537876}

chrome/browser/ui/views/tabs/tab.cc

@@ -611,9 +611,10 @@ void Tab::PaintChildren(const views::PaintInfo& info) {
   // except when the tab is too narrow to completely show even one icon, at
   // which point this serves to clip the favicon.
   ui::ClipRecorder clip_recorder(info.context());
-  clip_recorder.ClipPathWithAntiAliasing(
-      GetInteriorPath(info.context().device_scale_factor(), size(),
-                      GetTabEndcapWidth(), 1 /* padding */));
+  // The paint recording scale for tabs is consistent along the x and y axis.
+  const float paint_recording_scale = info.paint_recording_scale_x();
+  clip_recorder.ClipPathWithAntiAliasing(GetInteriorPath(
+      paint_recording_scale, size(), GetTabEndcapWidth(), 1 /* padding */));
   View::PaintChildren(info);
 }