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

components/gcm_driver/gcm_client.h

Index: components/gcm_driver/gcm_client.h
diff --git a/components/gcm_driver/gcm_client.h b/components/gcm_driver/gcm_client.h
index 4b216842a7eb10d054706889fadf15373c0d489e..c7f0aa958645d0ac7eac1881cf891ea615409f1d 100644
--- a/components/gcm_driver/gcm_client.h
+++ b/components/gcm_driver/gcm_client.h
@@ -103,6 +103,7 @@ class GCMClient {
   // Detailed information of the Send Error event.
   struct SendErrorDetails {
     SendErrorDetails();
+    SendErrorDetails(const SendErrorDetails& other);
     ~SendErrorDetails();
 
     std::string message_id;
@@ -114,6 +115,7 @@ class GCMClient {
   struct GCMStatistics {
    public:
     GCMStatistics();
+    GCMStatistics(const GCMStatistics& other);
     ~GCMStatistics();
 
     bool is_recording;