Revert 'Bypass UIWebView.scrollView's contentInset implementation with UIScrollView's.

ios/web/public/web_state/crw_web_view_scroll_view_proxy.h

 // Copyright 2014 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.
 
 #ifndef IOS_WEB_PUBLIC_WEB_STATE_CRW_WEB_VIEW_SCROLL_VIEW_PROXY_H_
 #define IOS_WEB_PUBLIC_WEB_STATE_CRW_WEB_VIEW_SCROLL_VIEW_PROXY_H_
 
 #import <UIKit/UIKit.h>
 
 @protocol CRWWebViewScrollViewProxyObserver;
@@ skipping 18 matching lines @@
 @property(nonatomic, assign) UIEdgeInsets scrollIndicatorInsets;
 @property(nonatomic, assign) CGSize contentSize;
 @property(nonatomic, readonly) CGRect frame;
 @property(nonatomic, getter=isScrollEnabled) BOOL scrollEnabled;
 @property(nonatomic, assign) BOOL bounces;
 @property(weak, nonatomic, readonly)
     UIPanGestureRecognizer* panGestureRecognizer;
 // Returns the scrollview's gesture recognizers.
 @property(weak, nonatomic, readonly) NSArray* gestureRecognizers;
 
-// Calls UIScrollView's implementation of setContentInset: directly. This
-// bypasses a very slow update path in UIWebView.
-- (void)setContentInsetFast:(UIEdgeInsets)contentInset;
-
 - (void)addGestureRecognizer:(UIGestureRecognizer*)gestureRecognizer;
 - (void)removeGestureRecognizer:(UIGestureRecognizer*)gestureRecognizer;
 - (void)setContentOffset:(CGPoint)contentOffset animated:(BOOL)animated;
 
 // Used by the CRWWebViewProxy to set the UIScrollView to be managed.
 - (void)setScrollView:(UIScrollView*)scrollView;
 
 // Adds |observer| to subscribe to change notifications.
 - (void)addObserver:(id<CRWWebViewScrollViewProxyObserver>)observer;
 
@@ skipping 36 matching lines @@
 // It inherit from CRWWebViewScrollViewScrollViewObserver which only implements
 // methods for listening to scrollview changes.
 @protocol CRWWebViewScrollViewProxyObserver<CRWWebViewScrollViewObserver>
 @optional
 // Called when the underlying scrollview of the proxy is set.
 - (void)webViewScrollViewProxyDidSetScrollView:
         (CRWWebViewScrollViewProxy*)webViewScrollViewProxy;
 @end
 
 #endif  // IOS_WEB_PUBLIC_WEB_STATE_CRW_WEB_VIEW_SCROLL_VIEW_PROXY_H_