[Mac][Material Design] Change toolbar buttons to 24x24 from 28x28.

chrome/browser/ui/toolbar/toolbar_actions_bar.cc

Index: chrome/browser/ui/toolbar/toolbar_actions_bar.cc
diff --git a/chrome/browser/ui/toolbar/toolbar_actions_bar.cc b/chrome/browser/ui/toolbar/toolbar_actions_bar.cc
index 546acd47f92fd9d1fdeb97a5689438e0ac188593..d7c564009808627984fd730f7ba05d3bb69ad891 100644
--- a/chrome/browser/ui/toolbar/toolbar_actions_bar.cc
+++ b/chrome/browser/ui/toolbar/toolbar_actions_bar.cc
@@ -45,8 +45,13 @@ enum DimensionType { WIDTH, HEIGHT };
 
 // Returns the width or height of the toolbar action icon size.
 int GetIconDimension(DimensionType type) {
-  if (ui::MaterialDesignController::IsModeMaterial())
+if (ui::MaterialDesignController::IsModeMaterial())
+#if defined(OS_MACOSX)
+  // On the Mac, the spec is a 24x24 button in a 28x28 space.
+    return 24;
+#else
     return 28;
+#endif
 
   static bool initialized = false;
   static int icon_height = 0;