[ios] Snapshot for WebState

ios/web/public/test/fakes/test_web_state.mm

 // Copyright 2014 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/public/test/fakes/test_web_state.h"
 
 #include <stdint.h>
 
+#include "base/bind.h"
 #include "base/callback.h"
+#include "base/threading/sequenced_task_runner_handle.h"
 #import "ios/web/public/web_state/ui/crw_content_view.h"
 #include "ios/web/public/web_state/web_state_observer.h"
+#include "ui/gfx/image/image.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 namespace web {
 
 void TestWebState::AddObserver(WebStateObserver* observer) {
   observers_.AddObserver(observer);
 }
@@ skipping 201 matching lines @@
 }
 
 WebStateInterfaceProvider* TestWebState::GetWebStateInterfaceProvider() {
   return nullptr;
 }
 
 bool TestWebState::HasOpener() const {
   return false;
 }
 
+void TestWebState::TakeSnapshot(const SnapshotCallback& callback,
+                                CGSize target_size) const {
+  base::SequencedTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE, base::Bind(callback, gfx::Image()));
+}
+
 base::WeakPtr<WebState> TestWebState::AsWeakPtr() {
   NOTREACHED();
   return base::WeakPtr<WebState>();
 }
 
 }  // namespace web