Add isWritableFileEntry to the fileSystem API

content/public/browser/child_process_security_policy.h

Index: content/public/browser/child_process_security_policy.h
diff --git a/content/public/browser/child_process_security_policy.h b/content/public/browser/child_process_security_policy.h
index 141713be3b01cdebc115be7c8547bdeb3a78ab69..7bfb68be33823fa1ff62585f6b81886477e43847 100644
--- a/content/public/browser/child_process_security_policy.h
+++ b/content/public/browser/child_process_security_policy.h
@@ -101,6 +101,11 @@ class ChildProcessSecurityPolicy {
   // |filesystem_id|.
   virtual bool CanReadFileSystem(int child_id,
                                  const std::string& filesystem_id) = 0;
+
+  // Returns true iff read and write access has been granted to the filesystem
+  // with |filesystem_id|.
+  virtual bool CanReadWriteFileSystem(int child_id,
+                                      const std::string& filesystem_id) = 0;
 };
 
 };  // namespace content