Pass WebState to VoiceController's StartRecognition instead of Tab.

Bug: 982030
Change-Id: I194cf28f8299667756332529cd13d2e6a7c113a7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1689926Reviewed-by: Mark Cogan <marq@chromium.org>
Commit-Queue: Mohammad Refaat <mrefaat@chromium.org>
Cr-Commit-Position: refs/heads/master@{#676941}

ios/chrome/browser/ui/browser_view/browser_view_controller.mm

@@ -1240,7 +1240,7 @@ NSString* const kBrowserViewControllerSnackbarCategory =
   [self ensureVoiceSearchControllerCreated];
 
   // Present voice search.
-  _voiceSearchController->StartRecognition(self, self.tabModel.currentTab);
+  _voiceSearchController->StartRecognition(self, self.currentWebState);
   [self.dispatcher cancelOmniboxEdit];
 }