[GCM] Add basic collapse key support for upstream

google_apis/gcm/engine/gcm_store_impl.cc

Index: google_apis/gcm/engine/gcm_store_impl.cc
diff --git a/google_apis/gcm/engine/gcm_store_impl.cc b/google_apis/gcm/engine/gcm_store_impl.cc
index daf7d362fd90adb3005a612c7d894a872e4e2fd4..8c46ce04b6600b234334c4971d0fbdd5e21b33f8 100644
--- a/google_apis/gcm/engine/gcm_store_impl.cc
+++ b/google_apis/gcm/engine/gcm_store_impl.cc
@@ -710,6 +710,25 @@ bool GCMStoreImpl::AddOutgoingMessage(const std::string& persistent_id,
   return false;
 }
 
+void GCMStoreImpl::OverwriteOutgoingMessage(const std::string& persistent_id,
+                                            const MCSMessage& message,
+                                            const UpdateCallback& callback) {
+  DCHECK_EQ(message.tag(), kDataMessageStanzaTag);
+  std::string app_id = reinterpret_cast<const mcs_proto::DataMessageStanza*>(
+      &message.GetProtobuf())->from();

[fgorski, 2014/01/27 17:39:38]

app_id is stored in category

[Nicolas Zea, 2014/01/28 08:15:35]

from is supposed to store project id, and category stores package name, right?
Id seems a better key to use (and is also what the gcm_store_impl is using for
per-app message limits)

[fgorski, 2014/01/28 18:10:27]

Ok. For upstream messages the following holds true:
* to stores project Id, and that is what you want to use,
* from is set to an arbitrary string ("gcm@chrome.com"),
* category indeed stores app_id/package name.

From would be set to sender ID/project Id on downstream messages.

[Nicolas Zea, 2014/01/31 11:58:43]

Done.

+  DCHECK(!app_id.empty());
+  // There should already be pending messages for this app.
+  DCHECK(app_message_counts_.count(app_id));
+  // TODO(zea); consider verifying the specific message already exists.
+  blocking_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&GCMStoreImpl::Backend::AddOutgoingMessage,
+                 backend_,
+                 persistent_id,
+                 message,
+                 callback));
+}
+
 void GCMStoreImpl::RemoveOutgoingMessage(const std::string& persistent_id,
                                          const UpdateCallback& callback) {
   blocking_task_runner_->PostTask(