mediaview: Mount ARC documents provider file system volumes.

chrome/browser/chromeos/fileapi/file_system_backend.cc

Index: chrome/browser/chromeos/fileapi/file_system_backend.cc
diff --git a/chrome/browser/chromeos/fileapi/file_system_backend.cc b/chrome/browser/chromeos/fileapi/file_system_backend.cc
index 9992f284d652bc2040afdbfd20f34c188142c04f..0a77c063f164c80349f549eefeeda2a09c889e9d 100644
--- a/chrome/browser/chromeos/fileapi/file_system_backend.cc
+++ b/chrome/browser/chromeos/fileapi/file_system_backend.cc
@@ -11,6 +11,7 @@
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
+#include "chrome/browser/chromeos/arc/fileapi/arc_documents_provider_util.h"
 #include "chrome/browser/chromeos/fileapi/file_access_permissions.h"
 #include "chrome/browser/chromeos/fileapi/file_system_backend_delegate.h"
 #include "chrome/browser/media_galleries/fileapi/media_file_system_backend.h"
@@ -156,6 +157,21 @@ void FileSystemBackend::ResolveURL(const storage::FileSystemURL& url,
     std::string inner_mount_name = components[1];
     root_url += inner_mount_name + "/";
     name = inner_mount_name;
+  } else if (id == arc::kDocumentsProviderMountPointName) {
+    // For ARC documents provider file system, volumes are mounted per document
+    // provider root, so we need to fix up |root_url| to point to an individual
+    // root.
+    std::string authority;
+    std::string root_document_id;
+    base::FilePath unused_path;
+    if (!arc::ParseDocumentsProviderUrl(url, &authority, &root_document_id,
+                                        &unused_path)) {
+      callback.Run(GURL(root_url), std::string(),
+                   base::File::FILE_ERROR_SECURITY);
+      return;
+    }
+    root_url += authority + "/" + root_document_id + "/";
+    name = authority + ":" + root_document_id;
   } else {
     name = id;
   }