Moved TestBackgroundSyncController to MockBackgroundSyncController

This is the first in a series of patches to add a content setting to
Background Sync.

In particular, this change will enable adding a method to
BackgroundSyncController that returns a permission status and mocking
it for tests. We can't just add a method to the controller that
returns a granted permission - this would be risky, but we do want to
control permission during tests.

Original, 'big picture' patch: crrev.com/1673303002

TEST=Existing background sync tests don't break.
BUG=564052

Review URL: https://codereview.chromium.org/1695503004

Cr-Commit-Position: refs/heads/master@{#375646}
diff --git a/content/shell/browser/shell_browser_context.cc b/content/shell/browser/shell_browser_context.cc
index 31e1485..0eee3c36 100644
--- a/content/shell/browser/shell_browser_context.cc
+++ b/content/shell/browser/shell_browser_context.cc
@@ -14,13 +14,13 @@
 #include "base/path_service.h"
 #include "base/threading/thread.h"
 #include "build/build_config.h"
-#include "content/public/browser/background_sync_controller.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/storage_partition.h"
 #include "content/public/common/content_switches.h"
 #include "content/shell/browser/shell_download_manager_delegate.h"
 #include "content/shell/browser/shell_permission_manager.h"
 #include "content/shell/common/shell_switches.h"
+#include "content/test/mock_background_sync_controller.h"
 
 #if defined(OS_WIN)
 #include "base/base_paths_win.h"
@@ -209,7 +209,7 @@
 
 BackgroundSyncController* ShellBrowserContext::GetBackgroundSyncController() {
   if (!background_sync_controller_)
-    background_sync_controller_.reset(new BackgroundSyncController());
+    background_sync_controller_.reset(new MockBackgroundSyncController());
   return background_sync_controller_.get();
 }