Cleanup: Pass std::string as const reference if possible

chrome/common/icon_with_badge_image_source.cc

Index: chrome/common/icon_with_badge_image_source.cc
diff --git a/chrome/common/icon_with_badge_image_source.cc b/chrome/common/icon_with_badge_image_source.cc
index 1afdbeee9830d53db8b3d4f8cb0e881b1c8afe37..b1cad82f56448892c42f4d5ed0396ebc02826e75 100644
--- a/chrome/common/icon_with_badge_image_source.cc
+++ b/chrome/common/icon_with_badge_image_source.cc
@@ -11,11 +11,10 @@
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/image/image_skia_operations.h"
 
-IconWithBadgeImageSource::Badge::Badge(std::string text,
+IconWithBadgeImageSource::Badge::Badge(const std::string& text,
                                        SkColor text_color,
                                        SkColor background_color)
-    : text(text), text_color(text_color), background_color(background_color) {
-}
+    : text(text), text_color(text_color), background_color(background_color) {}
 
 IconWithBadgeImageSource::Badge::~Badge() {}