Actually disable Wallet card saving on Linux.

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

 // Copyright 2014 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.
 
 #include "chrome/browser/ui/views/autofill/card_unmask_prompt_views.h"
 
 #include "base/basictypes.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/ui/autofill/autofill_dialog_types.h"
 #include "chrome/browser/ui/autofill/card_unmask_prompt_controller.h"
@@ skipping 310 matching lines @@
         IDS_AUTOFILL_CARD_UNMASK_INVALID_EXPIRATION_DATE));
   }
 
   GetDialogClientView()->UpdateDialogButtons();
 }
 
 void CardUnmaskPromptViews::AnimationProgressed(
     const gfx::Animation* animation) {
   uint8_t alpha = static_cast<uint8_t>(animation->CurrentValueBetween(0, 255));
   progress_overlay_->SetAlpha(alpha);
-  storage_row_->SetAlpha(255 - alpha);
+  if (storage_row_)
+    storage_row_->SetAlpha(255 - alpha);
 }
 
 void CardUnmaskPromptViews::InitIfNecessary() {
   if (has_children())
     return;
 
   main_contents_ = new views::View();
   main_contents_->SetLayoutManager(
       new views::BoxLayout(views::BoxLayout::kVertical, 0, 0, 12));
   AddChildView(main_contents_);
@@ skipping 134 matching lines @@
   views::View::OnPaint(canvas);
   canvas->Restore();
 }
 
 void CardUnmaskPromptViews::FadeOutView::SetAlpha(uint8_t alpha) {
   alpha_ = alpha;
   SchedulePaint();
 }
 
 }  // namespace autofill