Refactor the offline page storage to include client namespace and id.

components/offline_pages/proto/offline_pages.proto

Index: components/offline_pages/proto/offline_pages.proto
diff --git a/components/offline_pages/proto/offline_pages.proto b/components/offline_pages/proto/offline_pages.proto
index aeab8b0c193ebf7f2cf64fa4ead9240dcbf31f5d..d67c2e95c83b175773b4587d8876131d9c62ac1b 100644
--- a/components/offline_pages/proto/offline_pages.proto
+++ b/components/offline_pages/proto/offline_pages.proto
@@ -12,18 +12,28 @@ option retain_unknown_fields = true;
 
 package offline_pages;
 
+// ClientID represents an identified in the API Client's namespace.  It is mapped to an offline_id which

[Dmitry Titov, 2016/02/12 21:46:51]

Is there a need to map this client-provided info into offline_id? I'd rather
not, because we want the offline_id to be unique and that's it. The data
provided by clients is the client's business. For example, "Last N pages"
feature would simply provide namespace and empty id since it does not need to
store additional data separately.

I think we should just autogenerate offline_id rather that compute it form
ClientId.

[bburns, 2016/02/20 01:14:18]

Done.

+// serves as the primary key for offline storage.
+message ClientId {
+  optional string space = 1;
+  optional string id = 2;
+}
+
 message OfflinePageEntry {
   // URL of the offline page.
-  required string url = 1;
+  optional string url = 1;
 
   // Bookmark ID of the offline page.
-  required int64 bookmark_id = 2;
+  optional int64 deprecated_bookmark_id = 2;
+
+  // Offline ID of the page.  Offline ID has replaced Bookmark ID as the primary key
+  optional int64 offline_id = 10;
 
   // Version of the offline page metadata.
-  required int32 version = 3;
+  optional int32 version = 3;
 
   // Path to the offline archive.
-  required string file_path = 4;
+  optional string file_path = 4;
 
   // Size of the offline archive.
   optional int64 file_size = 5;
@@ -48,4 +58,7 @@ message OfflinePageEntry {
 
   // Flags for the offline page.
   optional Flags flags = 9;
+
+  // ClientID for this entry, used for reverse lookups.
+  optional ClientId client_id = 11;
 }