Don't focus voiceSearch button when VoiceOver is enabled.

BUG=1096303

Change-Id: Ib8ab6c447f11da6ddb37275fed67ec8e2946d141
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2405937Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: Mike Pinkerton <pinkerton@chromium.org>
Auto-Submit: Mike Pinkerton <pinkerton@chromium.org>
Cr-Commit-Position: refs/heads/master@{#806676}

ios/chrome/browser/ui/content_suggestions/content_suggestions_header_view_controller.mm

@@ -340,7 +340,7 @@ const NSString* kScribbleFakeboxElementId = @"fakebox";
   [self.headerView.voiceSearchButton addTarget:self
                                         action:@selector(preloadVoiceSearch:)
                               forControlEvents:UIControlEventTouchDown];
-  self.headerView.voiceSearchButton.enabled = self.voiceSearchIsEnabled;
+  [self updateVoiceSearchDisplay];
 }
 
 // On NTP in split toolbar mode the omnibox has different location (in the
@@ -476,6 +476,15 @@ const NSString* kScribbleFakeboxElementId = @"fakebox";
   }
 }
 
+// Ensures the state of the Voice Search button matches whether or not it's
+// enabled. If it's not, disables the button and removes it from the a11y loop
+// for VoiceOver.
+- (void)updateVoiceSearchDisplay {
+  self.headerView.voiceSearchButton.enabled = self.voiceSearchIsEnabled;
+  self.headerView.voiceSearchButton.isAccessibilityElement =
+      self.voiceSearchIsEnabled;
+}
+
 // Adds the constraints for the |logoView|, the |fakeomnibox| related to the
 // |headerView|. It also sets the properties constraints related to those views.
 - (void)addConstraintsForLogoView:(UIView*)logoView
@@ -700,7 +709,7 @@ const NSString* kScribbleFakeboxElementId = @"fakebox";
   if (_voiceSearchIsEnabled == voiceSearchIsEnabled)
     return;
   _voiceSearchIsEnabled = voiceSearchIsEnabled;
-  self.headerView.voiceSearchButton.enabled = _voiceSearchIsEnabled;
+  [self updateVoiceSearchDisplay];
 }
 
 #pragma mark - UserAccountImageUpdateDelegate