Base: Don't check for thread restrictions when closing a file doesn't do IO.

base/files/file.h

Index: base/files/file.h
diff --git a/base/files/file.h b/base/files/file.h
index a8cb16cb45722aa14523a1e28d74e85f2f61c238..8597473cc7a47ea381ce08c5b7646ea35524fa83 100644
--- a/base/files/file.h
+++ b/base/files/file.h
@@ -171,7 +171,11 @@ class BASE_EXPORT File {
   // FLAG_CREATE_ALWAYS), and false otherwise.
   bool created() const { return created_; }
 
-  // Returns the OS result of opening this file.
+  // Returns the OS result of opening this file. Note that the way to verify
+  // the success of the operation is to use IsValid(), not this method:
+  //   File file(name, flags);
+  //   if (!file.IsValid())
+  //     return;
   Error error_details() const { return error_details_; }
 
   PlatformFile GetPlatformFile() const { return file_; }