[Mac] Refactor decoration divider code.

chrome/browser/ui/cocoa/location_bar/location_bar_decoration.mm

Index: chrome/browser/ui/cocoa/location_bar/location_bar_decoration.mm
diff --git a/chrome/browser/ui/cocoa/location_bar/location_bar_decoration.mm b/chrome/browser/ui/cocoa/location_bar/location_bar_decoration.mm
index a2ad4effcfd93fcd85b962bd3b500f5609c0c9b9..7e71011556d5265c088f219fc28df03b15840754 100644
--- a/chrome/browser/ui/cocoa/location_bar/location_bar_decoration.mm
+++ b/chrome/browser/ui/cocoa/location_bar/location_bar_decoration.mm
@@ -6,8 +6,10 @@
 
 #include "base/logging.h"
 #include "base/mac/scoped_nsobject.h"
+#include "chrome/browser/ui/cocoa/l10n_util.h"
 #include "chrome/browser/ui/cocoa/omnibox/omnibox_view_mac.h"
 #include "skia/ext/skia_utils_mac.h"
+#import "ui/base/cocoa/nsview_additions.h"
 #import "ui/base/cocoa/tracking_area.h"
 #include "ui/gfx/color_palette.h"
 #include "ui/gfx/font.h"
@@ -16,7 +18,9 @@
 
 namespace {
 
-// Gray values for the bubble decoration divider.
+// Layout and color values for the vertical divider.
+const CGFloat kDividerHeight = 16.0;
+const CGFloat kDividerPadding = 6.0;  // Between the divider and label.
 const CGFloat kDividerGray = 0xFFA6A6A6;
 const CGFloat kDividerGrayIncognito = 0xFFDFDFDF;
 
@@ -159,6 +163,10 @@ LocationBarDecoration::~LocationBarDecoration() {
   [accessibility_view_.get() removeFromSuperview];
 }
 
+CGFloat LocationBarDecoration::DividerPadding() const {
+  return kDividerPadding;
+}
+
 bool LocationBarDecoration::IsVisible() const {
   return visible_;
 }
@@ -406,12 +414,55 @@ SkColor LocationBarDecoration::GetMaterialIconColor(
   return location_bar_is_dark ? SK_ColorWHITE : gfx::kChromeIconGrey;
 }
 
-NSColor* LocationBarDecoration::GetDividerColor(
-    bool location_bar_is_dark) const {
+void LocationBarDecoration::DrawDivider(NSView* control_view,
+                                        NSRect decoration_frame,
+                                        CGFloat alpha) const {
+  if (alpha == 0.0) {
+    return;
+  }
+
+  NSBezierPath* line = [NSBezierPath bezierPath];
+
+  CGFloat line_width = [control_view cr_lineWidth];
+  [line setLineWidth:line_width];
+
+  const BOOL is_rtl = cocoa_l10n_util::ShouldDoExperimentalRTLLayout();
+  NSPoint divider_origin = NSZeroPoint;
+  divider_origin.x = is_rtl ? NSMinX(decoration_frame) + DividerPadding()
+                            : NSMaxX(decoration_frame) - DividerPadding();
+  // Screen pixels lay between integral coordinates in user space. If you
+  // draw a line from (16, 16) to (16, 32), Core Graphics maps that line to
+  // the pixels that lay along x=16.5. In order to achieve a line that
+  // appears to lay along x=16, CG will perform dithering. To get a crisp
+  // line, you have to specify x=16.5, so translating by 1/2 the 1-pixel
+  // line width creates the crisp line we want. We subtract to better center
+  // the line between the label and URL.
+  divider_origin.x -= line_width / 2.;
+  CGFloat divider_y_frame_offset =
+      (NSHeight(decoration_frame) - kDividerHeight) / 2.0;
+  divider_origin.y = NSMinY(decoration_frame) + divider_y_frame_offset;
+  // Adjust the divider origin by 1/2 a point to visually center the
+  // divider vertically on Retina.
+  if (line_width < 1) {

[spqchan, 2017/05/05 23:00:15]

[optional nit]: No curly braces

[shrike, 2017/05/05 23:07:08]

Yeah, for simple if statements I opt for curly braces (I think it cuts down on
potential bugs).

+    divider_origin.y -= 0.5;
+  }
+  [line moveToPoint:divider_origin];
+  [line relativeLineToPoint:NSMakePoint(0, kDividerHeight)];
+
+  NSColor* divider_color = nil;
+  bool location_bar_is_dark =
+      [[control_view window] inIncognitoModeWithSystemTheme];
   if (location_bar_is_dark) {

[spqchan, 2017/05/05 23:00:15]

[optional nit]: No curly braces

-    return skia::SkColorToSRGBNSColor(kDividerGrayIncognito);
+    divider_color = skia::SkColorToSRGBNSColor(kDividerGrayIncognito);
+  } else {
+    divider_color = skia::SkColorToSRGBNSColor(kDividerGray);
+  }
+
+  if (alpha < 1) {
+    divider_color = [divider_color colorWithAlphaComponent:alpha];

[spqchan, 2017/05/05 23:00:15]

[optional nit]: No curly braces

   }
-  return skia::SkColorToSRGBNSColor(kDividerGray);
+  [divider_color set];
+  [line stroke];
 }
 
 const gfx::VectorIcon* LocationBarDecoration::GetMaterialVectorIcon() const {