[ios] Added web// public API to let embedder observe loading progress.

ios/web/web_state/web_state_impl.mm

 // Copyright 2013 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.
 
 #include "ios/web/web_state/web_state_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "base/strings/sys_string_conversions.h"
 #include "ios/web/interstitials/web_interstitial_impl.h"
 #import "ios/web/navigation/crw_session_controller.h"
 #import "ios/web/navigation/crw_session_entry.h"
 #include "ios/web/navigation/navigation_item_impl.h"
 #include "ios/web/net/request_group_util.h"
 #include "ios/web/public/browser_state.h"
 #include "ios/web/public/navigation_item.h"
 #include "ios/web/public/url_util.h"
 #include "ios/web/public/web_client.h"
 #include "ios/web/public/web_state/credential.h"
 #include "ios/web/public/web_state/ui/crw_content_view.h"
+#include "ios/web/public/web_state/web_state_delegate.h"
 #include "ios/web/public/web_state/web_state_observer.h"
 #include "ios/web/public/web_state/web_state_policy_decider.h"
 #include "ios/web/web_state/global_web_state_event_tracker.h"
 #import "ios/web/web_state/ui/crw_web_controller.h"
 #import "ios/web/web_state/ui/crw_web_controller_container_view.h"
 #include "ios/web/web_state/web_state_facade_delegate.h"
 #import "ios/web/webui/web_ui_ios_controller_factory_registry.h"
 #import "ios/web/webui/web_ui_ios_impl.h"
 #include "net/http/http_response_headers.h"
 
 namespace web {
 
 WebStateImpl::WebStateImpl(BrowserState* browser_state)
-    : is_loading_(false),
+    : delegate_(nullptr),
+      is_loading_(false),
       is_being_destroyed_(false),
       facade_delegate_(nullptr),
       web_controller_(nil),
       navigation_manager_(this, browser_state),
       interstitial_(nullptr),
       weak_factory_(this) {
   GlobalWebStateEventTracker::GetInstance()->OnWebStateCreated(this);
 }
 
 WebStateImpl::~WebStateImpl() {
   is_being_destroyed_ = true;
 
   // WebUI depends on web state so it must be destroyed first in case any WebUI
   // implementations depends on accessing web state during destruction.
   ClearWebUI();
 
   // The facade layer (owned by the delegate) should be destroyed before the web
   // layer.
   DCHECK(!facade_delegate_);
 
   FOR_EACH_OBSERVER(WebStateObserver, observers_, WebStateDestroyed());
   FOR_EACH_OBSERVER(WebStateObserver, observers_, ResetWebState());
   FOR_EACH_OBSERVER(WebStatePolicyDecider, policy_deciders_,
                     WebStateDestroyed());
   FOR_EACH_OBSERVER(WebStatePolicyDecider, policy_deciders_, ResetWebState());
   DCHECK(script_command_callbacks_.empty());
   if (request_tracker_.get())
     CloseRequestTracker();
+  SetDelegate(nullptr);
+}
+
+WebStateDelegate* WebStateImpl::GetDelegate() {
+  return delegate_;
+}
+
+void WebStateImpl::SetDelegate(WebStateDelegate* delegate) {
+  if (delegate == delegate_)
+    return;
+  if (delegate_)
+    delegate_->Detach(this);
+  delegate_ = delegate;
+  if (delegate_) {
+    delegate_->Attach(this);
+  }
 }
 
 void WebStateImpl::AddObserver(WebStateObserver* observer) {
   DCHECK(!observers_.HasObserver(observer));
   observers_.AddObserver(observer);
 }
 
 void WebStateImpl::RemoveObserver(WebStateObserver* observer) {
   DCHECK(observers_.HasObserver(observer));
   observers_.RemoveObserver(observer);
@@ skipping 286 matching lines @@
     web::WebInterstitial* interstitial = interstitial_;
     interstitial_ = nullptr;
     interstitial->DontProceed();
     // Don't access |interstitial| after calling |DontProceed()|, as it triggers
     // deletion.
     FOR_EACH_OBSERVER(WebStateObserver, observers_, InsterstitialDismissed());
   }
   [web_controller_ clearTransientContentView];
 }
 
+void WebStateImpl::SendChangeLoadProgress(double progress) {
+  if (delegate_) {
+    delegate_->LoadProgressChanged(this, progress);
+  }
+}
+
 WebUIIOS* WebStateImpl::CreateWebUIIOS(const GURL& url) {
   WebUIIOSControllerFactory* factory =
       WebUIIOSControllerFactoryRegistry::GetInstance();
   if (!factory)
     return NULL;
   WebUIIOSImpl* web_ui = new WebUIIOSImpl(this);
   WebUIIOSController* controller =
       factory->CreateWebUIIOSControllerForURL(web_ui, url);
   if (controller) {
     web_ui->SetController(controller);
@@ skipping 182 matching lines @@
     const LoadCommittedDetails& load_details) {
   FOR_EACH_OBSERVER(WebStateObserver, observers_,
                     NavigationItemCommitted(load_details));
 }
 
 WebState* WebStateImpl::GetWebState() {
   return this;
 }
 
 }  // namespace web