14 files declare their use of Container

bootstrap.inc in drupal/core/includes/bootstrap.inc
Functions that need to be loaded on every Drupal request.
Bundle.php in drupal/core/vendor/symfony/http-kernel/Symfony/Component/HttpKernel/Bundle/Bundle.php
common.inc in drupal/core/includes/common.inc
Common functions that many Drupal modules will need to reference.
ContainerAwareEventDispatcherTest.php in drupal/core/vendor/symfony/event-dispatcher/Symfony/Component/EventDispatcher/Tests/ContainerAwareEventDispatcherTest.php
ContainerBuilder.php in drupal/core/lib/Drupal/Core/DependencyInjection/ContainerBuilder.php
Definition of Drupal\Core\DependencyInjection\Container.
ContainerTest.php in drupal/core/vendor/symfony/dependency-injection/Symfony/Component/DependencyInjection/Tests/ContainerTest.php
ControllerResolverTest.php in drupal/core/modules/system/lib/Drupal/system/Tests/Routing/ControllerResolverTest.php
Definition of Drupal\system\Tests\Routing\ControllerResolverTest.
ExceptionController.php in drupal/core/lib/Drupal/Core/ExceptionController.php
Definition of Drupal\Core\ExceptionController.
Extension.php in drupal/core/vendor/symfony/http-kernel/Symfony/Component/HttpKernel/DependencyInjection/Extension.php
PhpDumper.php in drupal/core/vendor/symfony/dependency-injection/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php
services1.php in drupal/core/vendor/symfony/dependency-injection/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services1.php
services10.php in drupal/core/vendor/symfony/dependency-injection/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services10.php
services8.php in drupal/core/vendor/symfony/dependency-injection/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services8.php
services9.php in drupal/core/vendor/symfony/dependency-injection/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services9.php