[ios] Moves the Find in Page APIs into FindTabHelper.

ios/chrome/browser/find_in_page/find_in_page_controller.mm

 // Copyright 2012 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/chrome/browser/find_in_page/find_in_page_controller.h"
 
 #import <UIKit/UIKit.h>
 
 #import <cmath>
 #include <memory>
@@ skipping 250 matching lines @@
                                 atPoint:point];
     [[strongSelf webViewScrollView] setContentOffset:point animated:YES];
     if (completionHandler)
       completionHandler();
   }];
 }
 
 // Remove highlights from the page and disable the model.
 - (void)disableFindInPageWithCompletionHandler:
     (ProceduralBlock)completionHandler {
-  if (![self canFindInPage])
+  if (![self canFindInPage]) {
+    if (completionHandler)
+      completionHandler();
     return;
+  }
   // Cancel any queued calls to |recurringPumpWithCompletionHandler|.
   [NSObject cancelPreviousPerformRequestsWithTarget:self];
   __weak FindInPageController* weakSelf = self;
   ProceduralBlock handler = ^{
     FindInPageController* strongSelf = weakSelf;
     if (strongSelf) {
-      [strongSelf.findInPageModel setEnabled:NO];
       web::WebState* webState = [strongSelf webState];
       if (webState)
         DOMAlteringLock::FromWebState(webState)->Release(strongSelf);
     }
     if (completionHandler)
       completionHandler();
   };
   // Only run JSFindInPageManager disable if there is a string in progress to
   // avoid WKWebView crash on deallocation due to outstanding completion
   // handler.
@@ skipping 82 matching lines @@
 
 - (BOOL)canReleaseDOMLock {
   return NO;
 }
 
 - (void)releaseDOMLockWithCompletionHandler:(ProceduralBlock)completionHandler {
   NOTREACHED();
 }
 
 @end