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

components/gcm_driver/common/gcm_messages.cc

Index: components/gcm_driver/common/gcm_messages.cc
diff --git a/components/gcm_driver/common/gcm_messages.cc b/components/gcm_driver/common/gcm_messages.cc
index 1c092a345f34d04ab91fdc4eda2f4fb22ef079d6..35156ace48f433c2df746a310bcbe872dc94c246 100644
--- a/components/gcm_driver/common/gcm_messages.cc
+++ b/components/gcm_driver/common/gcm_messages.cc
@@ -12,12 +12,16 @@ const int OutgoingMessage::kMaximumTTL = 24 * 60 * 60;  // 1 day.
 OutgoingMessage::OutgoingMessage() : time_to_live(kMaximumTTL) {
 }
 
+OutgoingMessage::OutgoingMessage(const OutgoingMessage& other) = default;
+
 OutgoingMessage::~OutgoingMessage() {
 }
 
 IncomingMessage::IncomingMessage() : decrypted(false) {
 }
 
+IncomingMessage::IncomingMessage(const IncomingMessage& other) = default;
+
 IncomingMessage::~IncomingMessage() {
 }