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

ios/chrome/browser/ui/fullscreen_controller.mm

Index: ios/chrome/browser/ui/fullscreen_controller.mm
diff --git a/ios/chrome/browser/ui/fullscreen_controller.mm b/ios/chrome/browser/ui/fullscreen_controller.mm
index 83979807b80385479dbaad8892aaf4331259756f..441680faeb115473799d10766e2eb8b94987d3d2 100644
--- a/ios/chrome/browser/ui/fullscreen_controller.mm
+++ b/ios/chrome/browser/ui/fullscreen_controller.mm
@@ -687,8 +687,7 @@ BOOL CGFloatEquals(CGFloat a, CGFloat b) {
   [webViewProxy_ setTopContentPadding:newTopPadding];
 }
 
-- (void)setToolbarInsetsForHeaderOffset:(CGFloat)headerOffset
-                            forceUpdate:(BOOL)forceUpdate {
+- (void)setToolbarInsetsForHeaderOffset:(CGFloat)headerOffset {
   // Make space for the header in the scroll view.
   CGFloat topInset = self.headerHeight - headerOffset;
   UIEdgeInsets insets = self.scrollViewProxy.contentInset;
@@ -785,7 +784,7 @@ BOOL CGFloatEquals(CGFloat a, CGFloat b) {
 - (void)webViewScrollViewProxyDidSetScrollView:
     (CRWWebViewScrollViewProxy*)webViewScrollViewProxy {
   webViewScrollViewProxy.contentOffset = CGPointMake(0.0, -self.headerHeight);
-  [self setToolbarInsetsForHeaderOffset:0.0 forceUpdate:YES];
+  [self setToolbarInsetsForHeaderOffset:0.0];
 }
 
 #pragma mark - UIGestureRecognizerDelegate