Make the Tab Grid conform to the View Revealing Animatee protocol.

When the Tab Grid is visible, set |scrollEnabled| to YES to allow the
user to switch between recent tabs, incognito, and regular browser, and
set to NO otherwise (when the Thumb Strip or Tab Strip are visible).

Change-Id: I61bd079d50c9ab27b7970dcacaf149438595a269
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2445881
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Auto-Submit: Roberto Moura <mouraroberto@google.com>
Cr-Commit-Position: refs/heads/master@{#813659}

ios/chrome/browser/ui/tab_grid/BUILD.gn

@@ -112,6 +112,7 @@ source_set("tab_grid_ui") {
     "//ios/chrome/browser/ui/recent_tabs:recent_tabs_ui",
     "//ios/chrome/browser/ui/tab_grid/transitions",
     "//ios/chrome/browser/ui/table_view:styler",
+    "//ios/chrome/browser/ui/thumb_strip:feature_flags",
     "//ios/chrome/browser/ui/util",
     "//ios/chrome/common/ui/util",
     "//ios/web/public",

ios/chrome/browser/ui/tab_grid/tab_grid_coordinator.mm

@@ -351,6 +351,7 @@
     [self.thumbStripCoordinator start];
     self.thumbStripCoordinator.panHandler.layoutSwitcherProvider =
         baseViewController;
+    [self.thumbStripCoordinator.panHandler addAnimatee:baseViewController];
 
     [self setUpThumbStripAttachers];
   }

ios/chrome/browser/ui/tab_grid/tab_grid_view_controller.h

@@ -8,6 +8,7 @@
 #import <UIKit/UIKit.h>
 
 #import "ios/chrome/browser/ui/gestures/layout_switcher_provider.h"
+#import "ios/chrome/browser/ui/gestures/view_revealing_animatee.h"
 #import "ios/chrome/browser/ui/tab_grid/tab_grid_paging.h"
 #import "ios/chrome/browser/ui/tab_grid/transitions/grid_transition_animation_layout_providing.h"
 
@@ -32,7 +33,8 @@
 @interface TabGridViewController
     : UIViewController <GridTransitionAnimationLayoutProviding,
                         LayoutSwitcherProvider,
-                        TabGridPaging>
+                        TabGridPaging,
+                        ViewRevealingAnimatee>
 
 @property(nonatomic, weak) id<ApplicationCommands> handler;
 

ios/chrome/browser/ui/tab_grid/tab_grid_view_controller.mm

@@ -28,6 +28,7 @@
 #import "ios/chrome/browser/ui/tab_grid/tab_grid_top_toolbar.h"
 #import "ios/chrome/browser/ui/tab_grid/transitions/grid_transition_layout.h"
 #import "ios/chrome/browser/ui/table_view/chrome_table_view_styler.h"
+#import "ios/chrome/browser/ui/thumb_strip/thumb_strip_feature.h"
 #include "ios/chrome/browser/ui/ui_feature_flags.h"
 #import "ios/chrome/browser/ui/util/rtl_geometry.h"
 #import "ios/chrome/browser/ui/util/uikit_ui_util.h"
@@ -434,6 +435,21 @@ NSUInteger GetPageIndexFromPage(TabGridPage page) {
   return [self gridViewControllerForPage:self.activePage];
 }
 
+#pragma mark - ViewRevealingAnimatee
+
+- (void)willAnimateViewReveal:(ViewRevealState)currentViewRevealState {
+  self.scrollView.scrollEnabled = NO;
+}
+
+- (void)animateViewReveal:(ViewRevealState)viewRevealState {
+}
+
+- (void)didAnimateViewReveal:(ViewRevealState)viewRevealState {
+  if (viewRevealState == ViewRevealState::Revealed) {
+    self.scrollView.scrollEnabled = YES;
+  }
+}
+
 #pragma mark - Private
 
 // Sets the proper insets for the Remote Tabs ViewController to accomodate for
@@ -611,6 +627,9 @@ NSUInteger GetPageIndexFromPage(TabGridPage page) {
   self.scrollContentView = contentView;
   self.scrollView = scrollView;
   self.scrollView.accessibilityIdentifier = kTabGridScrollViewIdentifier;
+  if (IsThumbStripEnabled()) {
+    self.scrollView.scrollEnabled = NO;
+  }
   NSArray* constraints = @[
     [contentView.topAnchor constraintEqualToAnchor:scrollView.topAnchor],
     [contentView.bottomAnchor constraintEqualToAnchor:scrollView.bottomAnchor],