Move chrome.fileSystem implementation to //extensions

chrome/browser/extensions/api/chrome_extensions_api_client.cc

Index: chrome/browser/extensions/api/chrome_extensions_api_client.cc
diff --git a/chrome/browser/extensions/api/chrome_extensions_api_client.cc b/chrome/browser/extensions/api/chrome_extensions_api_client.cc
index 11c840f17ddbc2ed77e81ff90f07ee0bd4e5ae53..a570d506aeb2951e2e3cfd13669773312ac45408 100644
--- a/chrome/browser/extensions/api/chrome_extensions_api_client.cc
+++ b/chrome/browser/extensions/api/chrome_extensions_api_client.cc
@@ -12,6 +12,7 @@
 #include "chrome/browser/extensions/api/chrome_device_permissions_prompt.h"
 #include "chrome/browser/extensions/api/declarative_content/chrome_content_rules_registry.h"
 #include "chrome/browser/extensions/api/declarative_content/default_content_predicate_evaluators.h"
+#include "chrome/browser/extensions/api/file_system/chrome_file_system_delegate.h"
 #include "chrome/browser/extensions/api/management/chrome_management_api_delegate.h"
 #include "chrome/browser/extensions/api/metrics_private/chrome_metrics_private_delegate.h"
 #include "chrome/browser/extensions/api/networking_cast_private/chrome_networking_cast_private_delegate.h"
@@ -179,6 +180,12 @@ ChromeExtensionsAPIClient::GetNetworkingCastPrivateDelegate() {
   return networking_cast_private_delegate_.get();
 }
 
+FileSystemDelegate* ChromeExtensionsAPIClient::GetFileSystemDelegate() {
+  if (!file_system_delegate_)
+    file_system_delegate_ = base::MakeUnique<ChromeFileSystemDelegate>();
+  return file_system_delegate_.get();
+}
+
 #if defined(OS_CHROMEOS)
 NonNativeFileSystemDelegate*
 ChromeExtensionsAPIClient::GetNonNativeFileSystemDelegate() {