ipc: 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
R=jam@chromium.org, dcheng@chromium.org, thakis@chromium.org

Review URL: https://codereview.chromium.org/1731373003

Cr-Commit-Position: refs/heads/master@{#377390}


CrOS-Libchrome-Original-Commit: 665ede55ed8c60b7491dd87d82ebaa97bc10c873
diff --git a/ipc/attachment_broker.h b/ipc/attachment_broker.h
index d936f44..9bca157 100644
--- a/ipc/attachment_broker.h
+++ b/ipc/attachment_broker.h
@@ -142,6 +142,7 @@
 
   struct ObserverInfo {
     ObserverInfo();
+    ObserverInfo(const ObserverInfo& other);
     ~ObserverInfo();
 
     Observer* observer;