Add Mojo IPC for seeding new Renderer with Browser's cached blob state.

blimp/engine/mojo/blob_channel.mojom

Index: blimp/engine/mojo/blob_channel.mojom
diff --git a/blimp/engine/mojo/blob_channel.mojom b/blimp/engine/mojo/blob_channel.mojom
index 0960916fea10655f4e3511b8e2c1684108c08ace..6d02c2aeab1f390c81907ef4d874eee71b822c54 100644
--- a/blimp/engine/mojo/blob_channel.mojom
+++ b/blimp/engine/mojo/blob_channel.mojom
@@ -5,6 +5,12 @@
 module blimp.engine.mojom;
 
 interface BlobChannel {
+  // Gets the list of cache keys and their replication status in the

[Wez, 2016/07/01 00:30:20]

nit: list of cached BlobIds?

Suggest clarifying the mapping of replication status onto bool - e.g. true means
the Client has it?

[Kevin M, 2016/07/18 16:58:16]

Done.

+  // browser process' BlobCache.
+  // TODO(kmarshall): Add a delegate receiver to process cache invalidation
+  // events from the browser as they occur.
+  GetCachedBlobIds() => (map<string, bool> cache_state);
+
   // Stores the blob |id| in the BlobCache.
   // TODO(kmarshall): Use shared memory for more efficient data transfer, see
   // crbug.com/614564 .