Add |subviews| property to the scroll view

Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I084dedb73e3b5ccc0d958aef88c54e0d8cf820bd
Reviewed-on: https://chromium-review.googlesource.com/795492
Commit-Queue: Hiroshi Ichikawa <ichikawa@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#520809}

ios/web/public/web_state/ui/crw_web_view_scroll_view_proxy.h

@@ -42,6 +42,7 @@
     UIPanGestureRecognizer* panGestureRecognizer;
 // Returns the scrollview's gesture recognizers.
 @property(weak, nonatomic, readonly) NSArray* gestureRecognizers;
+@property(nonatomic, readonly, copy) NSArray<__kindof UIView*>* subviews;
 
 - (void)addGestureRecognizer:(UIGestureRecognizer*)gestureRecognizer;
 - (void)removeGestureRecognizer:(UIGestureRecognizer*)gestureRecognizer;

ios/web/web_state/ui/crw_web_view_scroll_view_proxy.mm

@@ -203,6 +203,10 @@
   return [_scrollView gestureRecognizers];
 }
 
+- (NSArray<__kindof UIView*>*)subviews {
+  return _scrollView ? [_scrollView subviews] : @[];
+}
+
 #pragma mark -
 #pragma mark UIScrollViewDelegate callbacks
 

ios/web/web_state/ui/crw_web_view_scroll_view_proxy_unittest.mm

@@ -126,6 +126,10 @@ TEST_F(CRWWebViewScrollViewProxyTest, ScrollViewPresent) {
   [[[mockScrollView_ expect] andReturnValue:@NO] scrollsToTop];
   EXPECT_FALSE([webViewScrollViewProxy_ scrollsToTop]);
 
+  NSArray<__kindof UIView*>* subviews = [NSArray array];
+  [[[mockScrollView_ expect] andReturn:subviews] subviews];
+  EXPECT_EQ(subviews, [webViewScrollViewProxy_ subviews]);
+
   if (@available(iOS 11, *)) {
     [[[mockScrollView_ expect]
         andReturnValue:@(UIScrollViewContentInsetAdjustmentAutomatic)]
@@ -159,6 +163,7 @@ TEST_F(CRWWebViewScrollViewProxyTest, ScrollViewAbsent) {
   EXPECT_FALSE([webViewScrollViewProxy_ isDragging]);
   EXPECT_FALSE([webViewScrollViewProxy_ isTracking]);
   EXPECT_FALSE([webViewScrollViewProxy_ scrollsToTop]);
+  EXPECT_EQ((NSUInteger)0, [webViewScrollViewProxy_ subviews].count);
   if (@available(iOS 11, *)) {
     EXPECT_EQ(UIScrollViewContentInsetAdjustmentAutomatic,
               [webViewScrollViewProxy_ contentInsetAdjustmentBehavior]);

ios/web_view/internal/cwv_scroll_view.mm

@@ -89,6 +89,10 @@
   return _proxy.panGestureRecognizer;
 }
 
+- (NSArray<__kindof UIView*>*)subviews {
+  return _proxy.subviews;
+}
+
 - (UIEdgeInsets)contentInset {
   return _proxy.contentInset;
 }

ios/web_view/public/cwv_scroll_view.h

@@ -36,6 +36,7 @@ CWV_EXPORT
     UIScrollViewContentInsetAdjustmentBehavior contentInsetAdjustmentBehavior
         API_AVAILABLE(ios(11.0));
 @property(nonatomic, readonly) UIPanGestureRecognizer* panGestureRecognizer;
+@property(nonatomic, readonly, copy) NSArray<__kindof UIView*>* subviews;
 
 // KVO compliant.
 @property(nonatomic, readonly) CGSize contentSize;