Convert zoom callbacks to use CallbackRegistry

chrome/browser/ui/gtk/location_bar_view_gtk_browsertest.cc

 // Copyright (c) 2012 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 <gtk/gtk.h>
 
 #include "base/strings/string_number_conversions.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_commands.h"
@@ skipping 94 matching lines @@
   GtkWidget* GetZoomWidget() {
     gfx::NativeWindow window = browser()->window()->GetNativeWindow();
     return ViewIDUtil::GetWidget(GTK_WIDGET(window), VIEW_ID_ZOOM_BUTTON);
   }
 
   void WaitForZoom(content::PageZoom zoom_action) {
     scoped_refptr<content::MessageLoopRunner> loop_runner(
         new content::MessageLoopRunner);
     content::HostZoomMap::ZoomLevelChangedCallback callback(
         base::Bind(&OnZoomLevelChanged, loop_runner->QuitClosure()));
-    content::HostZoomMap::GetForBrowserContext(
-        browser()->profile())->AddZoomLevelChangedCallback(callback);
+    scoped_ptr<content::HostZoomMap::Subscription> sub =
+        content::HostZoomMap::GetForBrowserContext(
+            browser()->profile())->AddZoomLevelChangedCallback(callback);
     chrome::Zoom(browser(), zoom_action);
     loop_runner->Run();
-    content::HostZoomMap::GetForBrowserContext(
-        browser()->profile())->RemoveZoomLevelChangedCallback(callback);
   }
 
   DISALLOW_COPY_AND_ASSIGN(LocationBarViewGtkZoomTest);
 };
 
 IN_PROC_BROWSER_TEST_F(LocationBarViewGtkZoomTest, DefaultToZoomedInAndBack) {
   content::WebContents* contents = SetUpTest();
 
   ZoomIn();
   ExpectZoomedIn(contents);
@@ skipping 47 matching lines @@
   DCHECK_LT(GetZoomPercent(contents), zoom_level);
   ExpectZoomedOut(contents);
   EXPECT_TRUE(ZoomIconIsShowing());
   ExpectIconIsResource(IDR_ZOOM_MINUS);
   ExpectTooltipContainsZoom();
 
   ResetZoom();
   ExpectAtDefaultZoom(contents);
   EXPECT_FALSE(ZoomIconIsShowing());
 }