For some vector icons, get the size from the vector definition.

ash/frame/caption_buttons/frame_caption_button.cc

Index: ash/frame/caption_buttons/frame_caption_button.cc
diff --git a/ash/frame/caption_buttons/frame_caption_button.cc b/ash/frame/caption_buttons/frame_caption_button.cc
index 07ced1fdd84644a6a9ba2c610b812adbb8ab216a..1705edcb56d927cec85b51206f95fc670fd7fb6f 100644
--- a/ash/frame/caption_buttons/frame_caption_button.cc
+++ b/ash/frame/caption_buttons/frame_caption_button.cc
@@ -58,8 +58,7 @@ void FrameCaptionButton::SetImage(CaptionButtonIcon icon,
                                   Animate animate,
                                   gfx::VectorIconId icon_image_id) {
   gfx::ImageSkia new_icon_image = gfx::CreateVectorIcon(
-      icon_image_id, 12,
-      use_light_images_ ? SK_ColorWHITE : gfx::kChromeIconGrey);
+      icon_image_id, use_light_images_ ? SK_ColorWHITE : gfx::kChromeIconGrey);
 
   // The early return is dependent on |animate| because callers use SetImage()
   // with ANIMATE_NO to progress the crossfade animation to the end.