Bug fix to add correct scale to the tab clip path

The clip path for tab is not being scaled based on the device scale
leading to incorrectly clipped tabs at HiDPI.

Bug: 812472
Change-Id: I4f016dec409dbd61eb569efc21eeab98dc3cfd74
Component: Tab, Clipping
Reviewed-on: https://chromium-review.googlesource.com/922454Reviewed-by: Peter Kasting <pkasting@chromium.org>
Commit-Queue: Malay Keshav <malaykeshav@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537122}

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

@@ -131,16 +131,19 @@ gfx::Path GetInteriorPath(float scale,
   // ClipPath with anti-aliasing enabled it can cause artifacts.
   const float bottom = std::ceil(size.height() * scale);
 
+  const float scaled_horizontal_inset = horizontal_inset * scale;
+
   // Construct the interior path by intersecting paths representing the left
   // and right halves of the tab.  Compared to computing the full path at once,
   // this makes it easier to avoid overdraw in the top center near minimum
   // width, and to implement cases where |horizontal_inset| != 0.
   gfx::Path right_path;
-  right_path.moveTo(right - 1 - horizontal_inset, bottom);
+  right_path.moveTo(right - 1 - scaled_horizontal_inset, bottom);
   right_path.rCubicTo(-0.75 * scale, 0, -1.625 * scale, -0.5 * scale,
                       -2 * scale, -1.5 * scale);
-  right_path.lineTo(right - 1 - horizontal_inset - (endcap_width - 2) * scale,
-                    2.5 * scale);
+  right_path.lineTo(
+      right - 1 - scaled_horizontal_inset - (endcap_width - 2) * scale,
+      2.5 * scale);
   right_path.rCubicTo(-0.375 * scale, -1 * scale, -1.25 * scale, -1.5 * scale,
                       -2 * scale, -1.5 * scale);
   right_path.lineTo(0, scale);
@@ -149,10 +152,11 @@ gfx::Path GetInteriorPath(float scale,
 
   gfx::Path left_path;
   const float scaled_endcap_width = 1 + endcap_width * scale;
-  left_path.moveTo(scaled_endcap_width + horizontal_inset, scale);
+  left_path.moveTo(scaled_endcap_width + scaled_horizontal_inset, scale);
   left_path.rCubicTo(-0.75 * scale, 0, -1.625 * scale, 0.5 * scale, -2 * scale,
                      1.5 * scale);
-  left_path.lineTo(1 + horizontal_inset + 2 * scale, bottom - 1.5 * scale);
+  left_path.lineTo(1 + scaled_horizontal_inset + 2 * scale,
+                   bottom - 1.5 * scale);
   left_path.rCubicTo(-0.375 * scale, scale, -1.25 * scale, 1.5 * scale,
                      -2 * scale, 1.5 * scale);
   left_path.lineTo(right, bottom);
@@ -607,8 +611,9 @@ 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(
-      1 /* scale */, size(), GetTabEndcapWidth(), 1 /* padding */));
+  clip_recorder.ClipPathWithAntiAliasing(
+      GetInteriorPath(info.context().device_scale_factor(), size(),
+                      GetTabEndcapWidth(), 1 /* padding */));
   View::PaintChildren(info);
 }