Modify WebBluetooth chooser based on UI review feedback

chrome/browser/ui/cocoa/chooser_content_view_cocoa.mm

Index: chrome/browser/ui/cocoa/chooser_content_view_cocoa.mm
diff --git a/chrome/browser/ui/cocoa/chooser_content_view_cocoa.mm b/chrome/browser/ui/cocoa/chooser_content_view_cocoa.mm
index 5df8fd3cdf20853640149a5a7bd5c1a2234f0e8c..409d5e41c537ac700067376fb782e7685e5dbab3 100644
--- a/chrome/browser/ui/cocoa/chooser_content_view_cocoa.mm
+++ b/chrome/browser/ui/cocoa/chooser_content_view_cocoa.mm
@@ -567,8 +567,9 @@ void ChooserContentViewController::UpdateTableView() {
 
     // Separator.
     CGFloat separatorOriginX = 0.0f;
-    CGFloat separatorOriginY = kMarginY + helpButtonHeight + kVerticalPadding;
-    [separator_ setFrameOrigin:NSMakePoint(separatorOriginX, separatorOriginY)];
+    separatorOriginY_ = kMarginY + helpButtonHeight + kVerticalPadding;
+    [separator_
+        setFrameOrigin:NSMakePoint(separatorOriginX, separatorOriginY_)];
     [self addSubview:separator_];
 
     // Help button.
@@ -878,4 +879,12 @@ void ChooserContentViewController::UpdateTableView() {
   return [tableRowView pairedStatus];
 }
 
+- (void)drawRect:(NSRect)rect {
+  [[NSColor colorWithCalibratedWhite:245.0f / 255.0f alpha:1.0f] setFill];
+  NSRect footnoteFrame =
+      NSMakeRect(0.0f, 0.0f, kChooserWidth, separatorOriginY_);
+  NSRectFill(footnoteFrame);
+  [super drawRect:footnoteFrame];
+}
+
 @end