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

components/gcm_driver/gcm_activity.cc

Index: components/gcm_driver/gcm_activity.cc
diff --git a/components/gcm_driver/gcm_activity.cc b/components/gcm_driver/gcm_activity.cc
index 192696d62022ef1626eb798bffc2bcfd8dd13e50..bee57d4b98820ab29ce67f0d217d84127bba39ad 100644
--- a/components/gcm_driver/gcm_activity.cc
+++ b/components/gcm_driver/gcm_activity.cc
@@ -53,6 +53,9 @@ DecryptionFailureActivity::~DecryptionFailureActivity() {
 RecordedActivities::RecordedActivities() {
 }
 
+RecordedActivities::RecordedActivities(const RecordedActivities& other) =
+    default;
+
 RecordedActivities::~RecordedActivities() {
 }