extensions: 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/1724293002

Cr-Commit-Position: refs/heads/master@{#378054}
diff --git a/extensions/browser/error_map.cc b/extensions/browser/error_map.cc
index dcf0101..5f94e34 100644
--- a/extensions/browser/error_map.cc
+++ b/extensions/browser/error_map.cc
@@ -37,6 +37,8 @@
       restrict_to_incognito(restrict_to_incognito) {
 }
 
+ErrorMap::Filter::Filter(const Filter& other) = default;
+
 ErrorMap::Filter::~Filter() {
 }