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

blimp/net/blob_channel/blob_channel_sender.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BLIMP_NET_BLOB_CHANNEL_BLOB_CHANNEL_SENDER_H_
 #define BLIMP_NET_BLOB_CHANNEL_BLOB_CHANNEL_SENDER_H_
 
+#include <vector>
+
 #include "blimp/common/blob_cache/blob_cache.h"
 #include "blimp/net/blimp_net_export.h"
 
 namespace blimp {
 
 class BLIMP_NET_EXPORT BlobChannelSender {
  public:
+  struct CacheStateEntry {
+    BlobId id;
+    bool was_delivered;
+  };
+
   virtual ~BlobChannelSender() {}
 
+  // Gets the list of cache keys and their replication status in the BlobCache.
+  virtual std::vector<CacheStateEntry> GetCachedBlobIds() const = 0;
+
   // Puts a blob in the local BlobChannel. The blob can then be pushed to the
   // remote receiver via "DeliverBlob()".
   // Does nothing if there is already a blob |id| in the channel.
   virtual void PutBlob(const BlobId& id, BlobDataPtr data) = 0;
 
   // Sends the blob |id| to the remote side, if the remote side doesn't already
   // have the blob.
   virtual void DeliverBlob(const BlobId& id) = 0;
 };
 
 }  // namespace blimp
 
 #endif  // BLIMP_NET_BLOB_CHANNEL_BLOB_CHANNEL_SENDER_H_