Move chrome.fileSystem implementation to //extensions

extensions/browser/api/extensions_api_client.h

Index: extensions/browser/api/extensions_api_client.h
diff --git a/extensions/browser/api/extensions_api_client.h b/extensions/browser/api/extensions_api_client.h
index e629818b90d42a046ac3e6a9fdc4d42485a5e947..3aff94b201fcc323cec683a011d00aab72f6cc59 100644
--- a/extensions/browser/api/extensions_api_client.h
+++ b/extensions/browser/api/extensions_api_client.h
@@ -35,6 +35,7 @@ class ContentRulesRegistry;
 class DevicePermissionsPrompt;
 class ExtensionOptionsGuest;
 class ExtensionOptionsGuestDelegate;
+class FileSystemDelegate;
 class ManagementAPIDelegate;
 class MetricsPrivateDelegate;
 class MimeHandlerViewGuest;
@@ -137,6 +138,9 @@ class ExtensionsAPIClient {
   // Creates a delegate for networking.castPrivate's API behavior.
   virtual NetworkingCastPrivateDelegate* GetNetworkingCastPrivateDelegate();
 
+  // Returns a delegate for embedder-specific chrome.fileSystem behavior.
+  virtual FileSystemDelegate* GetFileSystemDelegate();
+
 #if defined(OS_CHROMEOS)
   // If supported by the embedder, returns a delegate for querying non-native
   // file systems.