Make the header/content separator into a hairline for apps in hidpi

In order to make the hairline header/content separator look good in HiDPI
- The header/content separator overlays the window controls (to avoid a 1 physical pixel gap between the window controls and the header/content separator in 2x)
- This CL makes the window controls 2 physical pixels taller in 2x
- The bottom 1 physical pixel of the window control images is transparent. This is necessary because the window controls paint on top of the header/content separator

BUG=340135
TEST=Manual, see bug
R=jamescook@chromium.org

Review URL: https://codereview.chromium.org/200493004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@258301 0039d316-1c4b-4281-b951-d872f2087c98

ash/ash.gyp

@@ -177,8 +177,8 @@
         'frame/frame_border_hit_test_controller.h',
         'frame/default_header_painter.cc',
         'frame/default_header_painter.h',
-	'frame/frame_util.cc',
-	'frame/frame_util.h',
+	    'frame/frame_util.cc',
+	    'frame/frame_util.h',
         'frame/header_painter.h',
         'frame/header_painter_util.cc',
         'frame/header_painter_util.h',

ash/frame/custom_frame_view_ash_unittest.cc

@@ -113,19 +113,9 @@ TEST_F(CustomFrameViewAshTest, HeaderHeight) {
   gfx::ImageSkia* close_button =
       rb.GetImageSkiaNamed(IDR_AURA_WINDOW_CONTROL_BACKGROUND_H);
 
-  // |kSeparatorSize| should match |kHeaderContentSeparatorSize| in
-  // default_header_painter.cc
-  // TODO(pkotwicz): Clean this test up once the separator overlays the window
-  // controls.
-  const int kSeparatorSize = 1;
-
-  // The header should have enough room for the window controls and the
-  // separator line.
-  EXPECT_EQ(close_button->height() + kSeparatorSize,
-            delegate->custom_frame_view()->GetHeaderView()->height());
-
-  widget->Maximize();
-  EXPECT_EQ(close_button->height() + kSeparatorSize,
+  // The header should have enough room for the window controls. The
+  // header/content separator line overlays the window controls.
+  EXPECT_EQ(close_button->height(),
             delegate->custom_frame_view()->GetHeaderView()->height());
 }
 

ash/frame/default_header_painter.cc

@@ -30,8 +30,6 @@ namespace {
 
 // Color for the window title text.
 const SkColor kTitleTextColor = SkColorSetRGB(40, 40, 40);
-// Size of header/content separator line.
-const int kHeaderContentSeparatorSize = 1;
 // Color of the active window header/content separator line.
 const SkColor kHeaderContentSeparatorColor = SkColorSetRGB(180, 180, 182);
 // Color of the inactive window header/content separator line.
@@ -218,13 +216,14 @@ void DefaultHeaderPainter::LayoutHeader() {
     // Vertically center the window icon with respect to the caption button
     // container.
     int icon_size = HeaderPainterUtil::GetIconSize();
-    int icon_offset_y = (caption_button_container_->height() - icon_size) / 2;
+    // Floor when computing the center of |caption_button_container_|.
+    int icon_offset_y = caption_button_container_->height() / 2 - icon_size / 2;
     window_icon_->SetBounds(HeaderPainterUtil::GetIconXOffset(), icon_offset_y,
         icon_size, icon_size);
   }
 
-  SetHeaderHeightForPainting(caption_button_container_->height() +
-      kHeaderContentSeparatorSize);
+  // The header/content separator line overlays the caption buttons.
+  SetHeaderHeightForPainting(caption_button_container_->height());
 }
 
 int DefaultHeaderPainter::GetHeaderHeightForPainting() const {
@@ -300,11 +299,14 @@ void DefaultHeaderPainter::PaintHeaderContentSeparator(gfx::Canvas* canvas) {
       kHeaderContentSeparatorColor :
       kHeaderContentSeparatorInactiveColor;
 
-  canvas->FillRect(gfx::Rect(0,
-                             height_ - kHeaderContentSeparatorSize,
-                             view_->width(),
-                             kHeaderContentSeparatorSize),
-                   color);
+  SkPaint paint;
+  paint.setColor(color);
+  // Draw the line as 1px thick regardless of scale factor.
+  paint.setStrokeWidth(0);
+
+  float thickness = 1 / canvas->image_scale();
+  SkScalar y = SkIntToScalar(height_) - SkFloatToScalar(thickness);
+  canvas->sk_canvas()->drawLine(0, y, SkIntToScalar(view_->width()), y, paint);
 }
 
 gfx::Rect DefaultHeaderPainter::GetLocalBounds() const {

ash/frame/header_painter_util.cc

@@ -74,10 +74,9 @@ gfx::Rect HeaderPainterUtil::GetTitleBounds(
   int x = icon ?
       icon->bounds().right() + kTitleIconOffsetX : kTitleNoIconOffsetX;
   int height = title_font_list.GetHeight();
-  int y = std::max(
-      0,
-      static_cast<int>(std::ceil(
-          (caption_button_container->height() - height) / 2.0f)));
+  // Floor when computing the center of |caption_button_container| and when
+  // computing the center of the text.
+  int y = std::max(0, (caption_button_container->height() / 2) - (height / 2));
   int width = std::max(
       0, caption_button_container->x() - kTitleCaptionButtonSpacing - x);
   return gfx::Rect(x, y, width, height);