Extracting and unittesting PrepareDropDataForChildProcess function.

content/browser/fileapi/browser_file_system_helper.h

Index: content/browser/fileapi/browser_file_system_helper.h
diff --git a/content/browser/fileapi/browser_file_system_helper.h b/content/browser/fileapi/browser_file_system_helper.h
index c5702e73281631e88d65107a64ded88381796c68..b9679f9ea074e3b87c48b8a6c14d664976d3c1c8 100644
--- a/content/browser/fileapi/browser_file_system_helper.h
+++ b/content/browser/fileapi/browser_file_system_helper.h
@@ -17,6 +17,8 @@ class FileSystemURL;
 namespace content {
 
 class BrowserContext;
+class ChildProcessSecurityPolicyImpl;
+struct DropData;
 
 // Helper method that returns FileSystemContext constructed for
 // the browser process.
@@ -36,6 +38,24 @@ CONTENT_EXPORT void SyncGetPlatformPath(storage::FileSystemContext* context,
                                         int process_id,
                                         const GURL& path,
                                         base::FilePath* platform_path);
+
+// Make it possible for a |drop_data|'s resources to be read by |child_id|'s
+// process -- by granting permissions, rewriting |drop_data|, or both.
+//
+// |drop_data| can include references to local files and filesystem files that
+// were accessible to the child process that is the source of the drag and drop,
+// but might not (yet) be accessible to the child process that is the target of
+// the drop.  PrepareDropDataForChildProcess makes sure that |child_id| has
+// access to files referred to by |drop_data| - this method will 1) mutate
+// |drop_data| as needed (e.g. to refer to files in a new isolated filesystem,
+// rather than the original filesystem files) and 2) use |security_policy| to
+// grant |child_id| appropriate file access.
+CONTENT_EXPORT void PrepareDropDataForChildProcess(
+    DropData* drop_data,
+    ChildProcessSecurityPolicyImpl* security_policy,
+    int child_id,
+    const storage::FileSystemContext* file_system_context);
+
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FILEAPI_BROWSER_FILE_SYSTEM_HELPER_H_