Use floor instead of ceil for the size of the wallpaper layer.

ash/desktop_background/desktop_background_view.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 "ash/desktop_background/desktop_background_view.h"
 
 #include <limits>
 
 #include "ash/ash_export.h"
 #include "ash/desktop_background/desktop_background_controller.h"
 #include "ash/desktop_background/desktop_background_widget_controller.h"
 #include "ash/desktop_background/user_wallpaper_delegate.h"
 #include "ash/display/display_manager.h"
 #include "ash/root_window_controller.h"
 #include "ash/session/session_state_delegate.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
 #include "ash/wm/overview/window_selector_controller.h"
 #include "ash/wm/window_animations.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/utf_string_conversions.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/compositor/layer.h"
 #include "ui/gfx/canvas.h"
+#include "ui/gfx/geometry/safe_integer_conversions.h"
 #include "ui/gfx/geometry/size_conversions.h"
 #include "ui/gfx/image/image.h"
 #include "ui/gfx/transform.h"
 #include "ui/views/widget/widget.h"
 
 using wallpaper::WallpaperLayout;
 using wallpaper::WALLPAPER_LAYOUT_CENTER;
 using wallpaper::WALLPAPER_LAYOUT_CENTER_CROPPED;
 using wallpaper::WALLPAPER_LAYOUT_STRETCH;
 using wallpaper::WALLPAPER_LAYOUT_TILE;
 
 namespace ash {
 namespace {
 
-// For our scaling ratios we need to round positive numbers.
-int RoundPositive(double x) {
-  return static_cast<int>(floor(x + 0.5));
-}
-
 // A view that controls the child view's layer so that the layer
 // always has the same size as the display's original, un-scaled size
 // in DIP. The layer then transformed to fit to the virtual screen
 // size when laid-out.
 // This is to avoid scaling the image at painting time, then scaling
 // it back to the screen size in the compositor.
 class LayerControlView : public views::View {
  public:
   explicit LayerControlView(views::View* view) {
     AddChildView(view);
     view->SetPaintToLayer(true);
   }
 
   // Overrides views::View.
   void Layout() override {
     gfx::Display display = Shell::GetScreen()->GetDisplayNearestWindow(
         GetWidget()->GetNativeView());
     DisplayManager* display_manager = Shell::GetInstance()->display_manager();
     DisplayInfo info = display_manager->GetDisplayInfo(display.id());
     float ui_scale = info.GetEffectiveUIScale();
     gfx::SizeF pixel_size = display.size();
     pixel_size.Scale(1.0f / ui_scale);
-    gfx::Size rounded_size = gfx::ToCeiledSize(pixel_size);
+    gfx::Size rounded_size = gfx::ToFlooredSize(pixel_size);
     DCHECK_EQ(1, child_count());
     views::View* child = child_at(0);
     child->SetBounds(0, 0, rounded_size.width(), rounded_size.height());
     gfx::Transform transform;
     transform.Scale(ui_scale, ui_scale);
     child->SetTransform(transform);
   }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(LayerControlView);
@@ skipping 85 matching lines @@
     // The dimension with the smallest ratio must be cropped, the other one
     // is preserved. Both are set in gfx::Size cropped_size.
     double horizontal_ratio = static_cast<double>(width()) /
         static_cast<double>(wallpaper.width());
     double vertical_ratio = static_cast<double>(height()) /
         static_cast<double>(wallpaper.height());
 
     gfx::Size cropped_size;
     if (vertical_ratio > horizontal_ratio) {
       cropped_size = gfx::Size(
-          RoundPositive(static_cast<double>(width()) / vertical_ratio),
+          gfx::ToFlooredInt(static_cast<double>(width()) / vertical_ratio),
           wallpaper.height());
     } else {
-      cropped_size = gfx::Size(wallpaper.width(),
-          RoundPositive(static_cast<double>(height()) / horizontal_ratio));
+      cropped_size = gfx::Size(
+          wallpaper.width(),
+          gfx::ToFlooredInt(static_cast<double>(height()) / horizontal_ratio));
     }
 
     gfx::Rect wallpaper_cropped_rect(
         0, 0, wallpaper.width(), wallpaper.height());
     wallpaper_cropped_rect.ClampToCenteredSize(cropped_size);
     canvas->DrawImageInt(wallpaper,
         wallpaper_cropped_rect.x(), wallpaper_cropped_rect.y(),
         wallpaper_cropped_rect.width(), wallpaper_cropped_rect.height(),
         0, 0, width(), height(),
         true);
@@ skipping 73 matching lines @@
     // Disable animation if transition to login screen from an empty background.
     wm::SetWindowVisibilityAnimationTransition(
         desktop_widget->GetNativeView(), wm::ANIMATE_NONE);
   }
 
   desktop_widget->SetBounds(params.parent->bounds());
   return desktop_widget;
 }
 
 }  // namespace ash