Omnibox UI Experiments: Port vertical margin experiment to Cocoa.

chrome/browser/ui/cocoa/omnibox/omnibox_popup_cell.mm

 // Copyright 2013 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.
 
 #import "chrome/browser/ui/cocoa/omnibox/omnibox_popup_cell.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/i18n/rtl.h"
 #include "base/mac/foundation_util.h"
 #include "base/mac/objc_property_releaser.h"
 #include "base/mac/scoped_nsobject.h"
+#include "base/metrics/field_trial_params.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/ui/cocoa/omnibox/omnibox_popup_view_mac.h"
 #include "chrome/browser/ui/cocoa/omnibox/omnibox_view_mac.h"
 #import "chrome/browser/ui/cocoa/themed_window.h"
 #include "chrome/grit/generated_resources.h"
+#include "components/omnibox/browser/omnibox_field_trial.h"
 #include "components/omnibox/browser/omnibox_popup_model.h"
 #include "components/omnibox/browser/suggestion_answer.h"
 #include "skia/ext/skia_utils_mac.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/material_design/material_design_controller.h"
 #include "ui/gfx/color_palette.h"
 #include "ui/gfx/font.h"
 
 namespace {
 
-// How far to offset text.
-const CGFloat kVerticalTextPadding = 3.0;
+// Extra padding beyond the vertical text padding.
+constexpr CGFloat kMaterialExtraVerticalImagePadding = 2.0;
 
-const CGFloat kMaterialVerticalImagePadding = 5.0;
+constexpr CGFloat kMaterialTextStartOffset = 27.0;
 
-const CGFloat kMaterialTextStartOffset = 27.0;
+constexpr CGFloat kMaterialImageXOffset = 6.0;
 
-const CGFloat kMaterialImageXOffset = 6.0;
+// Returns the margin that should appear at the top and bottom of the result.
+CGFloat GetVerticalMargin() {
+  constexpr CGFloat kDefaultVerticalMargin = 3.0;
+
+  return base::GetFieldTrialParamByFeatureAsInt(
+      omnibox::kUIExperimentVerticalMargin,
+      OmniboxFieldTrial::kUIVerticalMarginParam, kDefaultVerticalMargin);
+}
 
 // Flips the given |rect| in context of the given |frame|.
 NSRect FlipIfRTL(NSRect rect, NSRect frame) {
   DCHECK_LE(NSMinX(frame), NSMinX(rect));
   DCHECK_GE(NSMaxX(frame), NSMaxX(rect));
   if (base::i18n::IsRTL()) {
     NSRect result = rect;
     result.origin.x = NSMinX(frame) + (NSMaxX(frame) - NSMaxX(rect));
     return result;
   }
@@ skipping 421 matching lines @@
       &contentsMaxWidth,
       &descriptionMaxWidth);
 
   NSWindow* parentWindow = [[controlView window] parentWindow];
   BOOL isDarkTheme = [parentWindow hasDarkTheme];
   NSRect imageRect = cellFrame;
   NSImage* theImage =
       isDarkTheme ? [cellData incognitoImage] : [cellData image];
   imageRect.size = [theImage size];
   imageRect.origin.x += kMaterialImageXOffset + [tableView contentLeftPadding];
-  imageRect.origin.y += kMaterialVerticalImagePadding;
+  imageRect.origin.y +=
+      GetVerticalMargin() + kMaterialExtraVerticalImagePadding;
   [theImage drawInRect:FlipIfRTL(imageRect, cellFrame)
               fromRect:NSZeroRect
              operation:NSCompositeSourceOver
               fraction:1.0
         respectFlipped:YES
                  hints:nil];
 
   NSPoint origin =
       NSMakePoint(kMaterialTextStartOffset + [tableView contentLeftPadding],
-                  kVerticalTextPadding);
+                  GetVerticalMargin());
   if ([cellData matchType] == AutocompleteMatchType::SEARCH_SUGGEST_TAIL) {
     // Tail suggestions are rendered with a prefix (usually ellipsis), which
     // appear vertically stacked.
     origin.x += [self drawMatchPrefixWithFrame:cellFrame
                                      tableView:tableView
                           withContentsMaxWidth:&contentsMaxWidth
                                   forDarkTheme:isDarkTheme];
   }
   origin.x += [self drawMatchPart:[cellData contents]
                         withFrame:cellFrame
                            origin:origin
                      withMaxWidth:contentsMaxWidth
                      forDarkTheme:isDarkTheme];
 
   if (descriptionMaxWidth > 0) {
     if ([cellData isAnswer]) {
-      origin =
-          NSMakePoint(kMaterialTextStartOffset + [tableView contentLeftPadding],
-                      kContentLineHeight - kVerticalTextPadding);
+      origin = NSMakePoint(
+          kMaterialTextStartOffset + [tableView contentLeftPadding],
+          [OmniboxPopupCell getContentTextHeight] - GetVerticalMargin());
       CGFloat imageSize = [tableView answerLineHeight];
       NSRect imageRect =
           NSMakeRect(NSMinX(cellFrame) + origin.x, NSMinY(cellFrame) + origin.y,
                      imageSize, imageSize);
       [[cellData answerImage] drawInRect:FlipIfRTL(imageRect, cellFrame)
                                 fromRect:NSZeroRect
                                operation:NSCompositeSourceOver
                                 fraction:1.0
                           respectFlipped:YES
                                    hints:nil];
       if ([cellData answerImage]) {
-        origin.x += imageSize + kMaterialVerticalImagePadding;
+        origin.x += imageSize + kMaterialImageXOffset;
 
         // Have to nudge the baseline down 1pt in Material Design for the text
         // that follows, so that it's the same as the bottom of the image.
         origin.y += 1;
       }
     } else {
       origin.x += [self drawMatchPart:[tableView separator]
                             withFrame:cellFrame
                                origin:origin
                          withMaxWidth:separatorWidth
@@ skipping 143 matching lines @@
 + (NSAttributedString*)createSeparatorStringForDarkTheme:(BOOL)isDarkTheme {
   base::string16 raw_separator =
       l10n_util::GetStringUTF16(IDS_AUTOCOMPLETE_MATCH_DESCRIPTION_SEPARATOR);
   return CreateAttributedString(raw_separator, DimTextColor(isDarkTheme));
 }
 
 + (CGFloat)getContentAreaWidth:(NSRect)cellFrame {
   return NSWidth(cellFrame) - kMaterialTextStartOffset;
 }
 
++ (CGFloat)getContentTextHeight {
+  constexpr CGFloat kDefaultTextHeight = 19;
+  return kDefaultTextHeight + 2 * GetVerticalMargin();
+}
+
 @end