views: Change CardUnmaskPromptViews::FadeOutView opacity to alpha.

chrome/browser/ui/views/autofill/card_unmask_prompt_views.h

Index: chrome/browser/ui/views/autofill/card_unmask_prompt_views.h
diff --git a/chrome/browser/ui/views/autofill/card_unmask_prompt_views.h b/chrome/browser/ui/views/autofill/card_unmask_prompt_views.h
index 03c4434e321ab993d0d4c3255b39d5a22134c64b..edac785eb50a0279caec240c2c2dd7391c33613c 100644
--- a/chrome/browser/ui/views/autofill/card_unmask_prompt_views.h
+++ b/chrome/browser/ui/views/autofill/card_unmask_prompt_views.h
@@ -94,9 +94,9 @@ class CardUnmaskPromptViews : public CardUnmaskPromptView,
     // is false, meaning only children are faded.
     bool fade_everything_;
 
-    // On a scale of 0-1, how much to fade out the contents of this view. 0 is
-    // totally invisible, 1 is totally visible.
-    double opacity_;
+    // The alpha channel for this view. 0 is transparent and 255 is opaque, and
+    // the value should always be inside that range.
+    int alpha_;
 
     DISALLOW_COPY_AND_ASSIGN(FadeOutView);
   };