Rounding error in HiDPI canvas.

ui/gfx/canvas_paint_win.h

 // Copyright (c) 2011 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.
 
 #ifndef UI_GFX_CANVAS_PAINT_WIN_H_
 #define UI_GFX_CANVAS_PAINT_WIN_H_
 
 #include "skia/ext/platform_canvas.h"
 #include "ui/base/win/dpi.h"
 #include "ui/gfx/canvas.h"
@@ skipping 103 matching lines @@
     RecreateBackingCanvas(gfx::Size(width, height),
         ui::GetScaleFactorFromScale(ui::win::GetDeviceScaleFactor()),
         opaque);
     skia::PlatformCanvas* canvas = platform_canvas();
 
     canvas->clear(SkColorSetARGB(0, 0, 0, 0));
 
     // This will bring the canvas into the screen coordinate system for the
     // dirty rect
     canvas->translate(
-        SkScalarRoundToInt(-ps_.rcPaint.left/ui::win::GetDeviceScaleFactor()),
-        SkScalarRoundToInt(-ps_.rcPaint.top/ui::win::GetDeviceScaleFactor()));
+        -ps_.rcPaint.left/ui::win::GetDeviceScaleFactor(),
+        -ps_.rcPaint.top/ui::win::GetDeviceScaleFactor());
   }
 
   // If true, this canvas was created for a BeginPaint.
   const bool for_paint_;
 
   // Disallow copy and assign.
   CanvasSkiaPaint(const CanvasSkiaPaint&);
   CanvasSkiaPaint& operator=(const CanvasSkiaPaint&);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_CANVAS_PAINT_WIN_H_