Reland "[iOS] Accessibility adjustments"

This is a reland of 1e910c7f.
It is safe to reland as a fix for the test has landed downstream.

Original change's description:
> [iOS] Accessibility adjustments
>
> This CL adds a delay for the voice over announcement of the InProduct
> Help tips. This delay is added to prevent the announcement to be
> cancelled by the element being focused, when the tab is presented.
> It also adds an accessibility label to the empty space where the omnibox
> should be if the toolbar was visible.
>
> Bug: 866936
> Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
> Change-Id: Ia75dd56772203e39b8d0bf1e94bef9cfacd87fdd
> Reviewed-on: https://chromium-review.googlesource.com/1158236
> Commit-Queue: edchin <edchin@chromium.org>
> Reviewed-by: edchin <edchin@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#579886}

TBR: edchin@chromium.org
Bug: 866936
Change-Id: I0c96e39827d4fb8f815664b10414314cad42a20c
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Reviewed-on: https://chromium-review.googlesource.com/1160661
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580203}

ios/chrome/browser/ui/bubble/bubble_view_controller_presenter.mm

@@ -24,6 +24,9 @@ const NSTimeInterval kBubbleVisibilityDuration = 5.0;
 // after the bubble first becomes visible.
 const NSTimeInterval kBubbleEngagementDuration = 30.0;
 
+// Delay before posting the VoiceOver notification.
+const CGFloat kVoiceOverAnnouncementDelay = 1;
+
 // The name for the histogram that tracks why a bubble was dismissed.
 const char kBubbleDismissalHistogramName[] = "IOS.IPHBubbleDismissalReason";
 
@@ -183,8 +186,21 @@ void LogBubbleDismissalReason(BubbleDismissalReason reason) {
                                       repeats:NO];
 
   if (self.voiceOverAnnouncement) {
-    UIAccessibilityPostNotification(UIAccessibilityAnnouncementNotification,
+    // The VoiceOverAnnouncement should be dispatched after a delay to account
+    // the fact that it can be presented right after a screen change (for
+    // example when the application or a new tab is opened). This screen change
+    // is changing the VoiceOver focus to focus a newly visible element. If this
+    // announcement is currently being read, it is cancelled. The added delay
+    // allows the announcement to be posted after the element is focused, so it
+    // is not cancelled.
+    dispatch_after(
+        dispatch_time(DISPATCH_TIME_NOW,
+                      (int64_t)(kVoiceOverAnnouncementDelay * NSEC_PER_SEC)),
+        dispatch_get_main_queue(), ^{
+          UIAccessibilityPostNotification(
+              UIAccessibilityAnnouncementNotification,
               self.voiceOverAnnouncement);
+        });
   }
 }
 

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

@@ -362,6 +362,8 @@ const UIEdgeInsets kSearchBoxStretchInsets = {3, 3, 3, 3};
 - (void)addFakeTapView {
   UIButton* fakeTapButton = [[UIButton alloc] init];
   fakeTapButton.translatesAutoresizingMaskIntoConstraints = NO;
+  fakeTapButton.accessibilityLabel =
+      l10n_util::GetNSString(IDS_ACCNAME_LOCATION);
   [self.headerView addToolbarView:fakeTapButton];
   [fakeTapButton addTarget:self
                     action:@selector(fakeOmniboxTapped:)