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 5fe40bda00de36d14313c364b0359bf7535b5cd7..ddffd0c0f46f478d691fd2f92d0ae26d6c917e52 100644
--- a/content/public/browser/child_process_security_policy.h
+++ b/content/public/browser/child_process_security_policy.h
@@ -100,6 +100,11 @@ 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