[Mac][Material Design] Rework how location bar shadow is drawn.

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

Index: chrome/browser/ui/cocoa/location_bar/autocomplete_text_field_cell.mm
diff --git a/chrome/browser/ui/cocoa/location_bar/autocomplete_text_field_cell.mm b/chrome/browser/ui/cocoa/location_bar/autocomplete_text_field_cell.mm
index 2bc741b3aae4ee02b7c3d3064189d7b71cd9dbb5..c27a489d8b2340f85c2e16bd8ed95371e06feb2d 100644
--- a/chrome/browser/ui/cocoa/location_bar/autocomplete_text_field_cell.mm
+++ b/chrome/browser/ui/cocoa/location_bar/autocomplete_text_field_cell.mm
@@ -317,10 +317,6 @@ size_t CalculatePositionsInFrame(
 
   // Compute the border's bezier path.
   NSRect pathRect = NSInsetRect(frame, insetSize, insetSize);
-  // In dark mode, make room for a shadow beneath the bottom edge.
-  if (inDarkMode && isModeMaterial) {
-    pathRect.size.height -= singlePixelLineWidth_;
-  }
   NSBezierPath* path =
       [NSBezierPath bezierPathWithRoundedRect:pathRect
                                       xRadius:kCornerRadius
@@ -369,7 +365,7 @@ size_t CalculatePositionsInFrame(
       }
 
       // Draw a highlight beneath the top edge, and a shadow beneath the bottom
-      // edge.
+      // edge when on a Retina screen.
       {
         gfx::ScopedNSGraphicsContextSaveGState saveState;
         [NSBezierPath setDefaultLineWidth:singlePixelLineWidth_];
@@ -383,10 +379,12 @@ size_t CalculatePositionsInFrame(
         [NSBezierPath strokeLineFromPoint:origin
                                   toPoint:destination];
 
-        origin.y = destination.y = NSMaxY(pathRect) + singlePixelLineWidth_;
-        [[NSColor colorWithCalibratedWhite:69 / 255. alpha:1] set];
-        [NSBezierPath strokeLineFromPoint:origin
-                                  toPoint:destination];
+        if (singlePixelLineWidth_ < 1) {
+          origin.y = destination.y = NSMaxY(pathRect) + singlePixelLineWidth_;
+          [[AutocompleteTextField shadowColor] set];
+          [NSBezierPath strokeLineFromPoint:origin
+                                    toPoint:destination];
+        }
       }
     }
   } else {