Implement CWVWebView.scrollView.

ios/web_view/internal/cwv_scroll_view.mm

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import "ios/web_view/public/cwv_scroll_view.h"
+
+#import "ios/web/public/web_state/ui/crw_web_view_scroll_view_proxy.h"
+#import "ios/web_view/internal/cwv_scroll_view_internal.h"
+#import "ios/web_view/public/cwv_scroll_view_delegate.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+@interface CWVScrollView ()<CRWWebViewScrollViewProxyObserver>
+
+// For KVO compliance, redefines the property as readwrite and calls its setter
+// when the value changes, instead of defining a getter which directly calls
+// _proxy.contentSize.
+@property(nonatomic, readwrite) CGSize contentSize;
+
+@end
+
+@implementation CWVScrollView
+
+@synthesize contentSize = _contentSize;
+@synthesize delegate = _delegate;
+@synthesize proxy = _proxy;
+
+- (void)setProxy:(nullable CRWWebViewScrollViewProxy*)proxy {
+  [_proxy removeObserver:self];
+  _proxy = proxy;
+  self.contentSize = _proxy.contentSize;
+  [_proxy addObserver:self];
+}
+
+- (CGPoint)contentOffset {
+  return _proxy.contentOffset;
+}
+
+- (void)setContentOffset:(CGPoint)contentOffset {
+  _proxy.contentOffset = contentOffset;
+}
+
+- (CGRect)bounds {
+  return {_proxy.contentOffset, _proxy.frame.size};
+}
+
+- (BOOL)isDragging {
+  return _proxy.dragging;
+}
+
+- (UIEdgeInsets)contentInset {
+  return _proxy.contentInset;
+}
+
+- (void)setContentInset:(UIEdgeInsets)contentInset {
+  _proxy.contentInset = contentInset;
+}
+
+- (void)addGestureRecognizer:(UIGestureRecognizer*)gestureRecognizer {
+  [_proxy addGestureRecognizer:gestureRecognizer];
+}
+
+#pragma mark - CRWWebViewScrollViewObserver
+
+- (void)webViewScrollViewWillBeginDragging:
+    (CRWWebViewScrollViewProxy*)webViewScrollViewProxy {
+  SEL selector = @selector(webViewScrollViewWillBeginDragging:);
+  if ([_delegate respondsToSelector:selector]) {
+    [_delegate scrollViewWillBeginDragging:self];
+  }
+}
+- (void)webViewScrollViewWillEndDragging:
+            (CRWWebViewScrollViewProxy*)webViewScrollViewProxy
+                            withVelocity:(CGPoint)velocity
+                     targetContentOffset:(inout CGPoint*)targetContentOffset {
+  SEL selector = @selector
+      (webViewScrollViewWillEndDragging:withVelocity:targetContentOffset:);
+  if ([_delegate respondsToSelector:selector]) {
+    [_delegate scrollViewWillEndDragging:self
+                            withVelocity:velocity
+                     targetContentOffset:targetContentOffset];
+  }
+}
+
+- (void)webViewScrollViewDidScroll:
+    (CRWWebViewScrollViewProxy*)webViewScrollViewProxy {
+  SEL selector = @selector(scrollViewDidScroll:);
+  if ([_delegate respondsToSelector:selector]) {
+    [_delegate scrollViewDidScroll:self];
+  }
+}
+
+- (void)webViewScrollViewDidEndDecelerating:
+    (CRWWebViewScrollViewProxy*)webViewScrollViewProxy {
+  SEL selector = @selector(webViewScrollViewDidEndDecelerating:);
+  if ([_delegate respondsToSelector:selector]) {
+    [_delegate scrollViewDidEndDecelerating:self];
+  }
+}
+
+- (void)webViewScrollViewDidResetContentSize:
+    (CRWWebViewScrollViewProxy*)webViewScrollViewProxy {
+  self.contentSize = _proxy.contentSize;
+}
+
+@end