chrome: 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]

Review URL: https://codereview.chromium.org/1731483003

Cr-Commit-Position: refs/heads/master@{#377767}
diff --git a/chrome/browser/extensions/install_signer.h b/chrome/browser/extensions/install_signer.h
index d2df9875..81d3d7af 100644
--- a/chrome/browser/extensions/install_signer.h
+++ b/chrome/browser/extensions/install_signer.h
@@ -47,6 +47,7 @@
   ExtensionIdSet invalid_ids;
 
   InstallSignature();
+  InstallSignature(const InstallSignature& other);
   ~InstallSignature();
 
   // Helper methods for serialization to/from a base::DictionaryValue.