Display the web view after commit for non-user-initiated loads.

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 499 matching lines @@
 - (void)removePlaceholderOverlay;
 
 // Creates a web view if it's not yet created.
 - (void)ensureWebViewCreated;
 // Creates a web view with given |config|. No-op if web view is already created.
 - (void)ensureWebViewCreatedWithConfiguration:(WKWebViewConfiguration*)config;
 // Returns a new autoreleased web view created with given configuration.
 - (WKWebView*)webViewWithConfiguration:(WKWebViewConfiguration*)config;
 // Sets the value of the webView property, and performs its basic setup.
 - (void)setWebView:(WKWebView*)webView;
+// Wraps the web view in a CRWWebViewContentView and adds it to the container
+// view.
+- (void)displayWebView;
 // Removes webView, optionally tracking the URL of the evicted
 // page for later cache-based reconstruction.
 - (void)removeWebViewAllowingCachedReconstruction:(BOOL)allowCache;
 // Called when web view process has been terminated.
 - (void)webViewWebProcessDidCrash;
 // Returns the WKWebViewConfigurationProvider associated with the web
 // controller's BrowserState.
 - (web::WKWebViewConfigurationProvider&)webViewConfigurationProvider;
 // Extracts "Referer" [sic] value from WKNavigationAction request header.
 - (NSString*)referrerFromNavigationAction:(WKNavigationAction*)action;
@@ skipping 3483 matching lines @@
         injectionEvaluator:self
                   delegate:self]);
 
     // Add all additional gesture recognizers to the web view.
     for (UIGestureRecognizer* recognizer in _gestureRecognizers.get()) {
       [_webView addGestureRecognizer:recognizer];
     }
 
     _URLOnStartLoading = _defaultURL;
 
-    // Add the web toolbars.
-    [_containerView addToolbars:_webViewToolbars];
+    // WKWebViews with invalid or empty frames have exhibited rendering bugs, so
+    // resize the view to match the container view upon creation.
+    [_webView setFrame:[_containerView bounds]];
 
-    base::scoped_nsobject<CRWWebViewContentView> webViewContentView(
-        [[CRWWebViewContentView alloc] initWithWebView:_webView
-                                            scrollView:self.webScrollView]);
-    [_containerView displayWebViewContentView:webViewContentView];
+    // If the visible NavigationItem should be loaded in this web view, display
+    // it immediately.  Otherwise, it will be displayed when the pending load is
+    // committed.
+    web::NavigationItem* visibleItem =
+        self.navigationManagerImpl->GetVisibleItem();
+    DCHECK(visibleItem);
+    if (![self shouldLoadURLInNativeView:visibleItem->GetURL()])
+      [self displayWebView];
   }
 }
 
 - (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);
 }
@@ skipping 32 matching lines @@
   }
   [_webView setNavigationDelegate:self];
   [_webView setUIDelegate:self];
   for (NSString* keyPath in self.WKWebViewObservers) {
     [_webView addObserver:self forKeyPath:keyPath options:0 context:nullptr];
   }
   _injectedScriptManagers.reset([[NSMutableSet alloc] init]);
   [self setDocumentURL:_defaultURL];
 }
 
+- (void)displayWebView {
+  if (!self.webView || [_containerView webViewContentView])

[Eugene But (OOO till 7-30), 2017/04/15 00:48:51]

When web view can be nil?

[kkhorimoto, 2017/04/17 23:42:09]

It really shouldn't be.  I've changed to use a DCHECK instead.

+    return;
+
+  // Add the web toolbars.
+  [_containerView addToolbars:_webViewToolbars];
+
+  base::scoped_nsobject<CRWWebViewContentView> webViewContentView(
+      [[CRWWebViewContentView alloc] initWithWebView:_webView
+                                          scrollView:self.webScrollView]);
+  [_containerView displayWebViewContentView:webViewContentView];
+}
+
 - (void)removeWebViewAllowingCachedReconstruction:(BOOL)allowCache {
   if (!_webView)
     return;
 
   _webStateImpl->CancelDialogs();
 
   web::NavigationItem* item = self.currentNavItem;
   if (allowCache && item) {
     _expectedReconstructionURL = item->GetVirtualURL();
   } else {
@@ skipping 392 matching lines @@
   }
 
   // This must be reset at the end, since code above may need information about
   // the pending load.
   _pendingNavigationInfo.reset();
   _certVerificationErrors->Clear();
 }
 
 - (void)webView:(WKWebView*)webView
     didCommitNavigation:(WKNavigation*)navigation {
+  [self displayWebView];
+
+  // Record the navigation state.
   [_navigationStates setState:web::WKNavigationState::COMMITTED
                 forNavigation:navigation];
 
   DCHECK_EQ(_webView, webView);
   _certVerificationErrors->Clear();
 
   // This is the point where the document's URL has actually changed, and
   // pending navigation information should be applied to state information.
   [self setDocumentURL:net::GURLWithNSURL([_webView URL])];
 
@@ skipping 387 matching lines @@
 - (BOOL)isLoadRequestPendingForURL:(const GURL&)targetURL {
   if (self.loadPhase != web::LOAD_REQUESTED)
     return NO;
 
   web::NavigationItem* pendingItem =
       self.webState->GetNavigationManager()->GetPendingItem();
   return pendingItem && pendingItem->GetURL() == targetURL;
 }
 
 - (void)loadRequestForCurrentNavigationItem {
-  DCHECK(_webView && !self.nativeController);
+  DCHECK(_webView);
   DCHECK(self.currentNavItem);
   // If a load is kicked off on a WKWebView with a frame whose size is {0, 0} or
   // that has a negative dimension for a size, rendering issues occur that
   // manifest in erroneous scrolling and tap handling (crbug.com/574996,
   // crbug.com/577793).
   DCHECK_GT(CGRectGetWidth([_webView frame]), 0.0);
   DCHECK_GT(CGRectGetHeight([_webView frame]), 0.0);
 
   web::WKBackForwardListItemHolder* holder =
       [self currentBackForwardListItemHolder];
@@ skipping 154 matching lines @@
 - (void)simulateLoadRequestWithURL:(const GURL&)URL {
   _lastRegisteredRequestURL = URL;
   _loadPhase = web::LOAD_REQUESTED;
 }
 
 - (NSString*)referrerFromNavigationAction:(WKNavigationAction*)action {
   return [action.request valueForHTTPHeaderField:kReferrerHeaderName];
 }
 
 @end