[iOS][iOS13][MF] Add composed layout guide and fix iPhone X

On iOS 13 the keyboard hierarchy was updated. Composing a layout guide
makes it transparent to the current while staying compatible with iOS
12.

Bug: 996669
Change-Id: I480c9955f911731ac4a30acc83519c9de03ecfdc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1765669
Commit-Queue: Javier Ernesto Flores Robles <javierrobles@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#692042}

ios/chrome/browser/ui/autofill/form_input_accessory/form_input_accessory_view_controller.mm

@@ -84,7 +84,7 @@ CGFloat const kInputAccessoryHeight = 44.0f;
 // used to constraint any presented view. iPad always presents in a separate
 // popover.
 - (BOOL)canPresentView {
-  return KeyboardObserverHelper.keyboardLayoutGuide || IsIPadIdiom();
+  return IsIPadIdiom() || KeyboardObserverHelper.keyboardLayoutGuide;
 }
 
 #pragma mark - Public

ios/chrome/browser/ui/util/keyboard_observer_helper.h

@@ -7,7 +7,7 @@
 
 #import <UIKit/UIKit.h>
 
-@protocol LayoutGuideProvider;
+@protocol EdgeLayoutGuideProvider;
 
 // Struct to track the current keyboard state.
 typedef struct {
@@ -49,7 +49,7 @@ typedef struct {
 // Best layout guide for the keyboard including the prediction part of it. |nil|
 // if the keyboard is not present or found.
 // This can break on any iOS update to keyboard architecture.
-@property(class, readonly, nonatomic) id<LayoutGuideProvider>
+@property(class, readonly, nonatomic) id<EdgeLayoutGuideProvider>
     keyboardLayoutGuide;
 
 // Flag that indicates if the keyboard is on screen.

ios/chrome/browser/ui/util/keyboard_observer_helper.mm

@@ -4,6 +4,7 @@
 
 #import "ios/chrome/browser/ui/util/keyboard_observer_helper.h"
 
+#include "base/logging.h"
 #include "ios/chrome/browser/ui/util/ui_util.h"
 #import "ios/chrome/common/ui_util/constraints_ui_util.h"
 
@@ -83,8 +84,22 @@
   return nil;
 }
 
-+ (id<LayoutGuideProvider>)keyboardLayoutGuide {
-  return [self keyboardLayoutGuideInHostView:self.keyboardView];
++ (id<EdgeLayoutGuideProvider>)keyboardLayoutGuide {
+  // [iOS 13] Sometimes there is an input assistant provided by the system.
+  // I.e. autocorrection or passwords. A composed guide is needed because
+  // there isn't a view "hugging" the accessory and the keyboard. This used to
+  // be merged with the keyboard < iOS 13.
+  //
+  // [iOS 13][iOS 12][iPhone][iPhoneX]: "Backdrop" works even when a picker is
+  // present.
+  for (NSString* name in @[ @"InputAssistant", @"Backdrop" ]) {
+    id<EdgeLayoutGuideProvider> layout =
+        [self keyboardLayoutGuideInHostView:self.keyboardView withName:name];
+    if (layout) {
+      return layout;
+    }
+  }
+  return nil;
 }
 
 #pragma mark - Keyboard Notifications
@@ -108,23 +123,32 @@
 
 #pragma mark - Private
 
+// Returns a layout guide defined by the top edge of |view| and its window.
++ (id<EdgeLayoutGuideProvider>)topEdgeLayoutGuideForView:(UIView*)view {
+  ComposedEdgeLayoutGuide* layoutGuide = [[ComposedEdgeLayoutGuide alloc] init];
+  layoutGuide.baseLayoutGuide = view.window;
+  layoutGuide.topAnchorProvider = view;
+  return layoutGuide;
+}
+
 // This searches in the passed view hierarchy for the best Layout Guide for the
-// keyboard.
-+ (id<LayoutGuideProvider>)keyboardLayoutGuideInHostView:(UIView*)hostView {
+// keyboard. Unexpected behaviour on iPad.
++ (id<EdgeLayoutGuideProvider>)keyboardLayoutGuideInHostView:(UIView*)hostView
+                                                    withName:(NSString*)name {
+  DCHECK(!IsIPadIdiom());
+
   for (UIView* subview in hostView.subviews) {
-    // Currently only tested on X-iOS12, 6+-iOS11 and 7+-iOS10. iPhoneX, iOS 11
-    // and 12 uses "Dock" and iOS 10 uses "Backdrop". iPhone6+, iOS 11 uses
-    // "Dock".
-    if ([NSStringFromClass([subview class]) containsString:@"Dock"] ||
-        [NSStringFromClass([subview class]) containsString:@"Backdrop"]) {
-      return subview;
+    if ([NSStringFromClass([subview class]) containsString:name]) {
+      return [self topEdgeLayoutGuideForView:subview];
     }
-    id<LayoutGuideProvider> found =
-        [self keyboardLayoutGuideInHostView:subview];
+    // Continue searching recursively.
+    id<EdgeLayoutGuideProvider> found =
+        [self keyboardLayoutGuideInHostView:subview withName:name];
     if (found) {
       return found;
     }
   }
+
   return nil;
 }
 

ios/chrome/common/ui_util/constraints_ui_util.h

@@ -50,14 +50,32 @@ inline ChromeDirectionalEdgeInsets ChromeDirectionalEdgeInsetsMake(
   return insets;
 }
 
-// Defines a protocol for common -...Anchor methods of UIView and UILayoutGuide.
-@protocol LayoutGuideProvider<NSObject>
+// Defines a protocol for the edge anchor methods of UIView and UILayoutGuide.
+@protocol EdgeLayoutGuideProvider <NSObject>
 @property(nonatomic, readonly, strong) NSLayoutXAxisAnchor* leadingAnchor;
 @property(nonatomic, readonly, strong) NSLayoutXAxisAnchor* trailingAnchor;
-@property(nonatomic, readonly, strong) NSLayoutXAxisAnchor* leftAnchor;
-@property(nonatomic, readonly, strong) NSLayoutXAxisAnchor* rightAnchor;
 @property(nonatomic, readonly, strong) NSLayoutYAxisAnchor* topAnchor;
 @property(nonatomic, readonly, strong) NSLayoutYAxisAnchor* bottomAnchor;
+@end
+
+// ComposedEdgeLayoutGuide is a layout guide based on the anchors of
+// multiple views. It is useful when the details of how the layout guide is
+// created shouldn't be exposed.
+@interface ComposedEdgeLayoutGuide : NSObject <EdgeLayoutGuideProvider>
+// A base layout guide to serve the anchors not defined with a provider.
+@property(nonatomic, weak) id<EdgeLayoutGuideProvider> baseLayoutGuide;
+// Each of the edge anchors can have a different provider assigned. If none is
+// assigned, the respective |baseLayoutGuide| anchor will be returned.
+@property(nonatomic, weak) id<EdgeLayoutGuideProvider> leadingAnchorProvider;
+@property(nonatomic, weak) id<EdgeLayoutGuideProvider> trailingAnchorProvider;
+@property(nonatomic, weak) id<EdgeLayoutGuideProvider> topAnchorProvider;
+@property(nonatomic, weak) id<EdgeLayoutGuideProvider> bottomAnchorProvider;
+@end
+
+// Defines a protocol for common -...Anchor methods of UIView and UILayoutGuide.
+@protocol LayoutGuideProvider <EdgeLayoutGuideProvider>
+@property(nonatomic, readonly, strong) NSLayoutXAxisAnchor* leftAnchor;
+@property(nonatomic, readonly, strong) NSLayoutXAxisAnchor* rightAnchor;
 @property(nonatomic, readonly, strong) NSLayoutDimension* widthAnchor;
 @property(nonatomic, readonly, strong) NSLayoutDimension* heightAnchor;
 @property(nonatomic, readonly, strong) NSLayoutXAxisAnchor* centerXAnchor;
@@ -133,24 +151,24 @@ void AddSameCenterYConstraint(UIView* unused_parentView,
 
 // Adds constraints to make two views' size and center equal by pinning leading,
 // trailing, top and bottom anchors.
-void AddSameConstraints(id<LayoutGuideProvider> view1,
-                        id<LayoutGuideProvider> view2);
+void AddSameConstraints(id<EdgeLayoutGuideProvider> view1,
+                        id<EdgeLayoutGuideProvider> view2);
 
 // Constraints all sides of |innerView| and |outerView| together, with
 // |innerView| inset by |insets|.
-void AddSameConstraintsWithInsets(id<LayoutGuideProvider> innerView,
-                                  id<LayoutGuideProvider> outerView,
+void AddSameConstraintsWithInsets(id<EdgeLayoutGuideProvider> innerView,
+                                  id<EdgeLayoutGuideProvider> outerView,
                                   ChromeDirectionalEdgeInsets insets);
 
 // Adds constraints to make |innerView| leading, trailing, top and bottom
 // anchors equals to |outerView| safe area (or view bounds) anchors.
-void PinToSafeArea(id<LayoutGuideProvider> innerView, UIView* outerView);
+void PinToSafeArea(id<EdgeLayoutGuideProvider> innerView, UIView* outerView);
 
 // Constraints |side_flags| of |view1| and |view2| together.
 // Example usage: AddSameConstraintsToSides(view1, view2,
 // LayoutSides::kTop|LayoutSides::kLeading)
-void AddSameConstraintsToSides(id<LayoutGuideProvider> view1,
-                               id<LayoutGuideProvider> view2,
+void AddSameConstraintsToSides(id<EdgeLayoutGuideProvider> view1,
+                               id<EdgeLayoutGuideProvider> view2,
                                LayoutSides side_flags);
 
 // Constraints |side_flags| sides of |innerView| and |outerView| together, with
@@ -160,8 +178,8 @@ void AddSameConstraintsToSides(id<LayoutGuideProvider> view1,
 // 10, 5}) - This will constraint innerView to be inside of outerView, with
 // leading/trailing inset by 10 and top/bottom inset by 5.
 // Edge insets for sides not listed in |side_flags| are ignored.
-void AddSameConstraintsToSidesWithInsets(id<LayoutGuideProvider> innerView,
-                                         id<LayoutGuideProvider> outerView,
+void AddSameConstraintsToSidesWithInsets(id<EdgeLayoutGuideProvider> innerView,
+                                         id<EdgeLayoutGuideProvider> outerView,
                                          LayoutSides side_flags,
                                          ChromeDirectionalEdgeInsets insets);
 
@@ -172,12 +190,12 @@ void AddSameConstraintsToSidesWithInsets(id<LayoutGuideProvider> innerView,
 // the padding is optional so that the inner views are not artificially
 // shortened when fixed-size cells cut into that padding.  The padding is added
 // between |outerView| and |innerView|.
-void AddOptionalVerticalPadding(id<LayoutGuideProvider> outerView,
-                                id<LayoutGuideProvider> innerView,
+void AddOptionalVerticalPadding(id<EdgeLayoutGuideProvider> outerView,
+                                id<EdgeLayoutGuideProvider> innerView,
                                 CGFloat padding);
-void AddOptionalVerticalPadding(id<LayoutGuideProvider> outerView,
-                                id<LayoutGuideProvider> topInnerView,
-                                id<LayoutGuideProvider> bottomInnerView,
+void AddOptionalVerticalPadding(id<EdgeLayoutGuideProvider> outerView,
+                                id<EdgeLayoutGuideProvider> topInnerView,
+                                id<EdgeLayoutGuideProvider> bottomInnerView,
                                 CGFloat padding);
 
 #pragma mark - Safe Area.

ios/chrome/common/ui_util/constraints_ui_util.mm

@@ -12,6 +12,24 @@
 #error "This file requires ARC support."
 #endif
 
+@implementation ComposedEdgeLayoutGuide
+- (NSLayoutXAxisAnchor*)leadingAnchor {
+  return self.leadingAnchorProvider.leadingAnchor
+             ?: self.baseLayoutGuide.leadingAnchor;
+}
+- (NSLayoutXAxisAnchor*)trailingAnchor {
+  return self.trailingAnchorProvider.trailingAnchor
+             ?: self.baseLayoutGuide.trailingAnchor;
+}
+- (NSLayoutYAxisAnchor*)topAnchor {
+  return self.topAnchorProvider.topAnchor ?: self.baseLayoutGuide.topAnchor;
+}
+- (NSLayoutYAxisAnchor*)bottomAnchor {
+  return self.bottomAnchorProvider.bottomAnchor
+             ?: self.baseLayoutGuide.bottomAnchor;
+}
+@end
+
 void ApplyVisualConstraints(NSArray* constraints,
                             NSDictionary* subviewsDictionary) {
   ApplyVisualConstraintsWithMetricsAndOptions(constraints, subviewsDictionary,
@@ -90,8 +108,8 @@ void AddSameCenterYConstraint(UIView* unused_parentView,
   AddSameCenterYConstraint(subview1, subview2);
 }
 
-void AddSameConstraints(id<LayoutGuideProvider> view1,
-                        id<LayoutGuideProvider> view2) {
+void AddSameConstraints(id<EdgeLayoutGuideProvider> view1,
+                        id<EdgeLayoutGuideProvider> view2) {
   [NSLayoutConstraint activateConstraints:@[
     [view1.leadingAnchor constraintEqualToAnchor:view2.leadingAnchor],
     [view1.trailingAnchor constraintEqualToAnchor:view2.trailingAnchor],
@@ -100,8 +118,8 @@ void AddSameConstraints(id<LayoutGuideProvider> view1,
   ]];
 }
 
-void AddSameConstraintsWithInsets(id<LayoutGuideProvider> innerView,
-                                  id<LayoutGuideProvider> outerView,
+void AddSameConstraintsWithInsets(id<EdgeLayoutGuideProvider> innerView,
+                                  id<EdgeLayoutGuideProvider> outerView,
                                   ChromeDirectionalEdgeInsets insets) {
   AddSameConstraintsToSidesWithInsets(
       innerView, outerView,
@@ -110,19 +128,19 @@ void AddSameConstraintsWithInsets(id<LayoutGuideProvider> innerView,
       insets);
 }
 
-void PinToSafeArea(id<LayoutGuideProvider> innerView, UIView* outerView) {
+void PinToSafeArea(id<EdgeLayoutGuideProvider> innerView, UIView* outerView) {
   AddSameConstraints(innerView, outerView.safeAreaLayoutGuide);
 }
 
-void AddSameConstraintsToSides(id<LayoutGuideProvider> view1,
-                               id<LayoutGuideProvider> view2,
+void AddSameConstraintsToSides(id<EdgeLayoutGuideProvider> view1,
+                               id<EdgeLayoutGuideProvider> view2,
                                LayoutSides side_flags) {
   AddSameConstraintsToSidesWithInsets(
       view1, view2, side_flags, ChromeDirectionalEdgeInsetsMake(0, 0, 0, 0));
 }
 
-void AddSameConstraintsToSidesWithInsets(id<LayoutGuideProvider> innerView,
-                                         id<LayoutGuideProvider> outerView,
+void AddSameConstraintsToSidesWithInsets(id<EdgeLayoutGuideProvider> innerView,
+                                         id<EdgeLayoutGuideProvider> outerView,
                                          LayoutSides side_flags,
                                          ChromeDirectionalEdgeInsets insets) {
   NSMutableArray* constraints = [[NSMutableArray alloc] init];
@@ -150,15 +168,15 @@ void AddSameConstraintsToSidesWithInsets(id<LayoutGuideProvider> innerView,
   [NSLayoutConstraint activateConstraints:constraints];
 }
 
-void AddOptionalVerticalPadding(id<LayoutGuideProvider> outerView,
-                                id<LayoutGuideProvider> innerView,
+void AddOptionalVerticalPadding(id<EdgeLayoutGuideProvider> outerView,
+                                id<EdgeLayoutGuideProvider> innerView,
                                 CGFloat padding) {
   AddOptionalVerticalPadding(outerView, innerView, innerView, padding);
 }
 
-void AddOptionalVerticalPadding(id<LayoutGuideProvider> outerView,
-                                id<LayoutGuideProvider> topInnerView,
-                                id<LayoutGuideProvider> bottomInnerView,
+void AddOptionalVerticalPadding(id<EdgeLayoutGuideProvider> outerView,
+                                id<EdgeLayoutGuideProvider> topInnerView,
+                                id<EdgeLayoutGuideProvider> bottomInnerView,
                                 CGFloat padding) {
   NSLayoutConstraint* topPaddingConstraint = [topInnerView.topAnchor
       constraintGreaterThanOrEqualToAnchor:outerView.topAnchor