base: Remove some unnecessary const scoped_refptr<>&.

This patch removes some unnecessary const scoped_refptr<>&. It replaces
some instances with a copy of scoped_refptr, followed by a move. Other
instances, it passes a raw non-owning pointer.

R=danakj
BUG=589044

Review URL: https://codereview.chromium.org/1800743003

Cr-Commit-Position: refs/heads/master@{#382043}
diff --git a/base/files/important_file_writer.h b/base/files/important_file_writer.h
index 1b2ad5c..4d18c0bd 100644
--- a/base/files/important_file_writer.h
+++ b/base/files/important_file_writer.h
@@ -63,11 +63,11 @@
   // execute file I/O operations.
   // All non-const methods, ctor and dtor must be called on the same thread.
   ImportantFileWriter(const FilePath& path,
-                      const scoped_refptr<SequencedTaskRunner>& task_runner);
+                      scoped_refptr<SequencedTaskRunner> task_runner);
 
   // Same as above, but with a custom commit interval.
   ImportantFileWriter(const FilePath& path,
-                      const scoped_refptr<SequencedTaskRunner>& task_runner,
+                      scoped_refptr<SequencedTaskRunner> task_runner,
                       TimeDelta interval);
 
   // You have to ensure that there are no pending writes at the moment