Fix memory management of VoiceSearchBarView.

ios/chrome/browser/ui/browser_view_controller.mm

Index: ios/chrome/browser/ui/browser_view_controller.mm
diff --git a/ios/chrome/browser/ui/browser_view_controller.mm b/ios/chrome/browser/ui/browser_view_controller.mm
index 31d9288756f9cc645d642ea12c8233fa411457e2..def7892dd117faa59be79d6cfdddfe7ac9bafc57 100644
--- a/ios/chrome/browser/ui/browser_view_controller.mm
+++ b/ios/chrome/browser/ui/browser_view_controller.mm
@@ -438,8 +438,7 @@ @interface BrowserViewController ()<AppRatingPromptDelegate,
   std::unique_ptr<InfoBarContainerDelegateIOS> _infoBarContainerDelegate;
 
   // Voice search bar at the bottom of the view overlayed on |_contentArea|
-  // when displaying voice search results. Implementation is not complete.
-  // See b/7998125.
+  // when displaying voice search results.
   base::scoped_nsprotocol<UIView<VoiceSearchBar>*> _voiceSearchBar;
 
   // The image fetcher used to save images and perform image-based searches.
@@ -2293,9 +2292,9 @@ - (void)ensureVoiceSearchBarCreated {
   CGFloat width = CGRectGetWidth([[self view] bounds]);
   CGFloat y = CGRectGetHeight([[self view] bounds]) - kVoiceSearchBarHeight;
   CGRect frame = CGRectMake(0.0, y, width, kVoiceSearchBarHeight);
-  _voiceSearchBar.reset(ios::GetChromeBrowserProvider()
-                            ->GetVoiceSearchProvider()
-                            ->CreateVoiceSearchBar(frame));
+  _voiceSearchBar.reset([ios::GetChromeBrowserProvider()
+                             ->GetVoiceSearchProvider()
+                             ->BuildVoiceSearchBar(frame) retain]);
   [_voiceSearchBar setVoiceSearchBarDelegate:self];
   [_voiceSearchBar setHidden:YES];
   [_voiceSearchBar setAutoresizingMask:UIViewAutoresizingFlexibleTopMargin |