components: Add out-of-line copy ctors for complex classes.

This patch adds out of line copy constructors for classes that our
clang-plugin considers heavy. This is an effort to enable copy
constructor checks by default.

BUG=436357
[email protected], [email protected], [email protected]

Review URL: https://codereview.chromium.org/1869063004

Cr-Commit-Position: refs/heads/master@{#386173}
diff --git a/components/drive/file_change.h b/components/drive/file_change.h
index 40d750c..1cfc6911 100644
--- a/components/drive/file_change.h
+++ b/components/drive/file_change.h
@@ -84,6 +84,7 @@
   typedef std::map<base::FilePath, FileChange::ChangeList> Map;
 
   FileChange();
+  FileChange(const FileChange& other);
   ~FileChange();
 
   void Update(const base::FilePath file_path,