diff --git a/app/code/Magento/PageCache/Observer/FlushCacheByTags.php b/app/code/Magento/PageCache/Observer/FlushCacheByTags.php
index 8ce26f7d31781..bcf5c9d328348 100644
--- a/app/code/Magento/PageCache/Observer/FlushCacheByTags.php
+++ b/app/code/Magento/PageCache/Observer/FlushCacheByTags.php
@@ -1,6 +1,5 @@
 <?php
 /**
- *
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
@@ -9,6 +8,9 @@
 use Magento\Framework\App\ObjectManager;
 use Magento\Framework\Event\ObserverInterface;
 
+/**
+ * Class to flush cache by tags
+ */
 class FlushCacheByTags implements ObserverInterface
 {
     /**
@@ -40,15 +42,25 @@ class FlushCacheByTags implements ObserverInterface
     /**
      * @param \Magento\PageCache\Model\Config $config
      * @param \Magento\Framework\App\PageCache\Cache $cache
+     * @param \Magento\Framework\App\Cache\Tag\Resolver $tagResolver
+     * @param \Magento\PageCache\Model\Cache\Type $fullPageCache
      */
-    public function __construct(\Magento\PageCache\Model\Config $config, \Magento\Framework\App\PageCache\Cache $cache)
-    {
+    public function __construct(
+        \Magento\PageCache\Model\Config $config,
+        \Magento\Framework\App\PageCache\Cache $cache,
+        \Magento\Framework\App\Cache\Tag\Resolver $tagResolver,
+        \Magento\PageCache\Model\Cache\Type $fullPageCache
+    ) {
         $this->_config = $config;
         $this->_cache = $cache;
+        $this->tagResolver = $tagResolver;
+        $this->fullPageCache = $fullPageCache;
     }
 
     /**
-     * If Built-In caching is enabled it collects array of tags
+     * Flushes cache
+     *
+     * If built-in caching is enabled it collects array of tags
      * of incoming object and asks to clean cache.
      *
      * @param \Magento\Framework\Event\Observer $observer
@@ -61,38 +73,11 @@ public function execute(\Magento\Framework\Event\Observer $observer)
             if (!is_object($object)) {
                 return;
             }
-            $tags = $this->getTagResolver()->getTags($object);
+            $tags = $this->tagResolver->getTags($object);
 
             if (!empty($tags)) {
-                $this->getCache()->clean(\Zend_Cache::CLEANING_MODE_MATCHING_ANY_TAG, array_unique($tags));
+                $this->fullPageCache->clean(\Zend_Cache::CLEANING_MODE_MATCHING_ANY_TAG, array_unique($tags));
             }
         }
     }
-
-    /**
-     * TODO: Workaround to support backwards compatibility, will rework to use Dependency Injection in MAGETWO-49547
-     *
-     *
-     * @return \Magento\PageCache\Model\Cache\Type
-     */
-    private function getCache()
-    {
-        if (!$this->fullPageCache) {
-            $this->fullPageCache = ObjectManager::getInstance()->get(\Magento\PageCache\Model\Cache\Type::class);
-        }
-        return $this->fullPageCache;
-    }
-
-    /**
-     * @deprecated 100.1.2
-     * @return \Magento\Framework\App\Cache\Tag\Resolver
-     */
-    private function getTagResolver()
-    {
-        if ($this->tagResolver === null) {
-            $this->tagResolver = \Magento\Framework\App\ObjectManager::getInstance()
-                ->get(\Magento\Framework\App\Cache\Tag\Resolver::class);
-        }
-        return $this->tagResolver;
-    }
 }
diff --git a/app/code/Magento/PageCache/Test/Unit/Observer/FlushCacheByTagsTest.php b/app/code/Magento/PageCache/Test/Unit/Observer/FlushCacheByTagsTest.php
index 8019c6b2e810f..de993e5a858e8 100644
--- a/app/code/Magento/PageCache/Test/Unit/Observer/FlushCacheByTagsTest.php
+++ b/app/code/Magento/PageCache/Test/Unit/Observer/FlushCacheByTagsTest.php
@@ -29,23 +29,17 @@ class FlushCacheByTagsTest extends \PHPUnit\Framework\TestCase
      */
     protected function setUp()
     {
-        $helper = new \Magento\Framework\TestFramework\Unit\Helper\ObjectManager($this);
         $this->_configMock = $this->createPartialMock(\Magento\PageCache\Model\Config::class, ['getType', 'isEnabled']);
         $this->_cacheMock = $this->createPartialMock(\Magento\Framework\App\PageCache\Cache::class, ['clean']);
+        $this->tagResolver = $this->createMock(\Magento\Framework\App\Cache\Tag\Resolver::class);
         $this->fullPageCacheMock = $this->createPartialMock(\Magento\PageCache\Model\Cache\Type::class, ['clean']);
 
         $this->_model = new \Magento\PageCache\Observer\FlushCacheByTags(
             $this->_configMock,
-            $this->_cacheMock
+            $this->_cacheMock,
+            $this->tagResolver,
+            $this->fullPageCacheMock
         );
-
-        $this->tagResolver = $this->createMock(\Magento\Framework\App\Cache\Tag\Resolver::class);
-
-        $helper->setBackwardCompatibleProperty($this->_model, 'tagResolver', $this->tagResolver);
-        $reflection = new \ReflectionClass(\Magento\PageCache\Observer\FlushCacheByTags::class);
-        $reflectionProperty = $reflection->getProperty('fullPageCache');
-        $reflectionProperty->setAccessible(true);
-        $reflectionProperty->setValue($this->_model, $this->fullPageCacheMock);
     }
 
     /**