[ios] Fix tab strip rtl long press frame.

Bug: 865119
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: Ic2a6fdb250075d14306eb4f581b8443f05632d8f
Reviewed-on: https://chromium-review.googlesource.com/1145851
Commit-Queue: Justin Cohen <justincohen@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577088}

ios/chrome/browser/ui/tabs/tab_strip_controller.mm

@@ -523,11 +523,6 @@ NSString* StringForItemCount(long count) {
 
 - (void)hideTabStrip:(BOOL)hidden {
   self.view.hidden = hidden;
-  if (!hidden) {
-    NamedGuide* tabSwitcherGuide =
-        [NamedGuide guideWithName:kTabStripTabSwitcherGuide view:self.view];
-    tabSwitcherGuide.constrainedView = _tabSwitcherButton;
-  }
 }
 
 #pragma mark - Private
@@ -751,6 +746,21 @@ NSString* StringForItemCount(long count) {
   return [self modelIndexForIndex:[_tabArray indexOfObject:view]];
 }
 
+// The |tabSwitcherGuide| cannot use constrainedView in the tab strip because
+// here views use CGAffineTransformMakeScale to support RTL, and NamedGuide
+// doesn't honor transforms. Instead we set the tabSwitcherGuide as necessary.
+- (void)updateTabSwitcherGuide {
+  NamedGuide* tabSwitcherGuide =
+      [NamedGuide guideWithName:kTabStripTabSwitcherGuide view:self.view];
+  tabSwitcherGuide.constrainedFrame = _tabSwitcherButton.frame;
+  if (UseRTLLayout()) {
+    CGRect frame = tabSwitcherGuide.constrainedFrame;
+    frame.origin.x =
+        self.view.frame.size.width - _tabSwitcherButton.frame.origin.x;
+    tabSwitcherGuide.constrainedFrame = frame;
+  }
+}
+
 #pragma mark -
 #pragma mark Tab Drag and Drop methods
 
@@ -1392,6 +1402,7 @@ NSString* StringForItemCount(long count) {
 // Creates TabViews for each Tab in the TabModel and positions them in the
 // correct location onscreen.
 - (void)layoutTabStripSubviews {
+  [self updateTabSwitcherGuide];
   const NSUInteger tabCount = [_tabArray count] - [_closingTabs count];
   if (!tabCount)
     return;