Re-land "Replace requirePageReconstruction with setCustomUserAgent"

ios/web/web_state/ui/crw_web_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/web/web_state/ui/crw_web_controller.h"
 
 #import <WebKit/WebKit.h>
 
 #import <objc/runtime.h>
 #include <stddef.h>
@@ skipping 458 matching lines @@
 // an error if the returned URL is not reliable from a security point of view.
 // Note that this method is expensive, so it should always be cached locally if
 // it's needed multiple times in a method.
 @property(nonatomic, readonly) GURL currentURL;
 // Returns the referrer for the current page.
 @property(nonatomic, readonly) web::Referrer currentReferrer;
 
 // Returns YES if the user interacted with the page recently.
 @property(nonatomic, readonly) BOOL userClickedRecently;
 
-// Whether or not desktop user agent is used for the currentItem.
-@property(nonatomic, readonly) BOOL usesDesktopUserAgent;
+// User agent type of the transient item if any, the pending item if a
+// navigation is in progress or the last committed item otherwise.
+// Returns MOBILE, the default type, if navigation manager is nullptr or empty.
+@property(nonatomic, readonly) web::UserAgentType userAgentType;
 
 // Facade for Mojo API.
 @property(nonatomic, readonly) web::MojoFacade* mojoFacade;
 
 // TODO(crbug.com/692871): Remove these functions and replace with more
 // appropriate NavigationItem getters.
 // Returns the navigation item for the current page.
 @property(nonatomic, readonly) web::NavigationItemImpl* currentNavItem;
 // Returns the current transition type.
 @property(nonatomic, readonly) ui::PageTransition currentTransition;
 // Returns the referrer for current navigation item. May be empty.
 @property(nonatomic, readonly) web::Referrer currentNavItemReferrer;
 // The HTTP headers associated with the current navigation item. These are nil
 // unless the request was a POST.
 @property(nonatomic, readonly) NSDictionary* currentHTTPHeaders;
 
-// Requires page reconstruction if |item| has a non-NONE UserAgentType and it
-// differs from that of |fromItem|.
-- (void)updateDesktopUserAgentForItem:(web::NavigationItem*)item
-                previousUserAgentType:(web::UserAgentType)userAgentType;
+// Updates web view's user agent according to |userAgentType|. It is no-op if
+// |userAgentType| is NONE.
+- (void)updateWebViewUserAgentFromUserAgentType:
+    (web::UserAgentType)userAgentType;
+
+// Requires that the next load rebuild the web view. This is expensive, and
+// should be used only in the case where something has changed that web view
+// only checks on creation, such that the whole object needs to be rebuilt.
+// TODO(stuartmorgan): Merge this and reinitializeWebViewAndReload:. They are
+// currently subtly different in terms of implementation, but are for
+// fundamentally the same purpose.
+- (void)requirePageReconstruction;
 
 // Removes the container view from the hierarchy and resets the ivar.
 - (void)resetContainerView;
 // Called when the web page has changed document and/or URL, and so the page
 // navigation should be reported to the delegate, and internal state updated to
 // reflect the fact that the navigation has occurred.
 // TODO(stuartmorgan): The code conflates URL changes and document object
 // changes; the two need to be separated and handled differently.
 - (void)webPageChanged;
 // Resets any state that is associated with a specific document object (e.g.,
@@ skipping 1118 matching lines @@
     [self didFinishWithURL:targetURL loadSuccess:NO];
     return;
   }
 
   // JavaScript should never be evaluated here. User-entered JS should be
   // evaluated via stringByEvaluatingUserJavaScriptFromString.
   DCHECK(!targetURL.SchemeIs(url::kJavaScriptScheme));
 
   [self ensureWebViewCreated];
 
+  // Update web view's user agent is called for every load, which may have
+  // performance implications because update web view's user agent may
+  // potentially send a message to a separate thread. However, this is not an
+  // issue for WKWebView because WKWebView's |setCustomUserAgent| is non-op if
+  // user agent stays thesame.
+  [self updateWebViewUserAgentFromUserAgentType:self.userAgentType];
+
   [self loadRequestForCurrentNavigationItem];
 }
 
 - (void)updatePendingNavigationInfoFromNavigationAction:
     (WKNavigationAction*)action {
   if (action.targetFrame.mainFrame) {
     _pendingNavigationInfo.reset(
         [[CRWWebControllerPendingNavigationInfo alloc] init]);
     [_pendingNavigationInfo
         setReferrer:[self referrerFromNavigationAction:action]];
@@ skipping 390 matching lines @@
     return;
   }
 
   if (!_webStateImpl->IsShowingWebInterstitial())
     [self recordStateInHistory];
 
   [self clearTransientContentView];
 
   // Update the user agent before attempting the navigation.
   web::NavigationItem* toItem = items[index].get();
-  web::NavigationItem* previousItem = sessionController.currentItem;
-  web::UserAgentType previousUserAgentType =
-      previousItem ? previousItem->GetUserAgentType()
-                   : web::UserAgentType::NONE;
-  [self updateDesktopUserAgentForItem:toItem
-                previousUserAgentType:previousUserAgentType];
+  [self updateWebViewUserAgentFromUserAgentType:toItem->GetUserAgentType()];
 
+  web::NavigationItem* fromItem = sessionController.currentItem;
   BOOL sameDocumentNavigation =
-      [sessionController isSameDocumentNavigationBetweenItem:previousItem
+      [sessionController isSameDocumentNavigationBetweenItem:fromItem
                                                      andItem:toItem];
   if (sameDocumentNavigation) {
     [sessionController goToItemAtIndex:index];
     [self updateHTML5HistoryState];
   } else {
     [sessionController discardNonCommittedItems];
     [sessionController setPendingItemIndex:index];
 
     web::NavigationItemImpl* pendingItem = sessionController.pendingItem;
     pendingItem->SetTransitionType(ui::PageTransitionFromInt(
@@ skipping 134 matching lines @@
   // The page should be closed if it was initiated by the DOM and there has been
   // no user interaction with the page since the web view was created, or if
   // the page has no navigation items, as occurs when an App Store link is
   // opened from another application.
   BOOL rendererInitiatedWithoutInteraction =
       self.hasOpener && !_userInteractedWithWebController;
   BOOL noNavigationItems = !(self.navigationManagerImpl->GetItemCount());
   return rendererInitiatedWithoutInteraction || noNavigationItems;
 }
 
-- (BOOL)usesDesktopUserAgent {
+- (web::UserAgentType)userAgentType {
   web::NavigationItem* item = self.currentNavItem;
-  return item && item->GetUserAgentType() == web::UserAgentType::DESKTOP;
+  return item ? item->GetUserAgentType() : web::UserAgentType::MOBILE;
 }
 
 - (web::MojoFacade*)mojoFacade {
   if (!_mojoFacade) {
     service_manager::mojom::InterfaceProvider* interfaceProvider =
         _webStateImpl->GetMojoInterfaceRegistry();
     _mojoFacade.reset(new web::MojoFacade(interfaceProvider, self));
   }
   return _mojoFacade.get();
 }
@@ skipping 18 matching lines @@
       [delegate webController:strongSelf didLoadPassKitObject:data];
     }
   };
   web::BrowserState* browserState = self.webStateImpl->GetBrowserState();
   _passKitDownloader.reset([[CRWPassKitDownloader alloc]
       initWithContextGetter:browserState->GetRequestContext()
           completionHandler:passKitCompletion]);
   return _passKitDownloader.get();
 }
 
-- (void)updateDesktopUserAgentForItem:(web::NavigationItem*)item
-                previousUserAgentType:(web::UserAgentType)userAgentType {
-  if (!item)
+- (void)updateWebViewUserAgentFromUserAgentType:
+    (web::UserAgentType)userAgentType {
+  if (userAgentType == web::UserAgentType::NONE)
     return;
-  web::UserAgentType itemUserAgentType = item->GetUserAgentType();
-  if (itemUserAgentType == web::UserAgentType::NONE)
-    return;
-  if (itemUserAgentType != userAgentType)
-    [self requirePageReconstruction];
+
+  NSString* userAgent =
+      base::SysUTF8ToNSString(web::GetWebClient()->GetUserAgent(userAgentType));
+  [_webView setCustomUserAgent:userAgent];
 }
 
 #pragma mark -
 #pragma mark CRWWebControllerContainerViewDelegate
 
 - (CRWWebViewProxyImpl*)contentViewProxyForContainerView:
         (CRWWebControllerContainerView*)containerView {
   return _webViewProxy.get();
 }
 
@@ skipping 1776 matching lines @@
                                             scrollView:self.webScrollView]);
     [_containerView displayWebViewContentView:webViewContentView];
   }
 }
 
 - (WKWebView*)webViewWithConfiguration:(WKWebViewConfiguration*)config {
   // Do not attach the context menu controller immediately as the JavaScript
   // delegate must be specified.
   return web::BuildWKWebView(CGRectZero, config,
                              self.webStateImpl->GetBrowserState(),
-                             self.usesDesktopUserAgent);
+                             self.userAgentType);
 }
 
 - (void)setWebView:(WKWebView*)webView {
   DCHECK_NE(_webView.get(), webView);
 
   // Unwind the old web view.
   // TODO(eugenebut): Remove CRWWKScriptMessageRouter once crbug.com/543374 is
   // fixed.
   CRWWKScriptMessageRouter* messageRouter =
       [self webViewConfigurationProvider].GetScriptMessageRouter();
@@ skipping 1043 matching lines @@
 - (void)simulateLoadRequestWithURL:(const GURL&)URL {
   _lastRegisteredRequestURL = URL;
   _loadPhase = web::LOAD_REQUESTED;
 }
 
 - (NSString*)referrerFromNavigationAction:(WKNavigationAction*)action {
   return [action.request valueForHTTPHeaderField:kReferrerHeaderName];
 }
 
 @end