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

blimp/net/blob_channel/blob_channel_sender_impl.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_IMPL_H_
 #define BLIMP_NET_BLOB_CHANNEL_BLOB_CHANNEL_SENDER_IMPL_H_
 
 #include <memory>
 #include <set>
 #include <string>
+#include <vector>
 
 #include "base/macros.h"
 #include "base/threading/thread_checker.h"
 #include "blimp/common/blob_cache/blob_cache.h"
 #include "blimp/net/blimp_net_export.h"
 #include "blimp/net/blob_channel/blob_channel_sender.h"
 
 namespace blimp {
 
 // Sends blobs to a remote receiver.
 // The transport-specific details are provided by the caller using the Delegate
 // subclass.
 class BLIMP_NET_EXPORT BlobChannelSenderImpl : public BlobChannelSender {
  public:
   // Delegate interface for transport-specific implementations of blob transfer
   // commands.
   class Delegate {
    public:
     virtual ~Delegate() {}
 
     // Send blob |id| with payload |data| to the receiver.
     virtual void DeliverBlob(const BlobId& id, BlobDataPtr data) = 0;
   };
 
   BlobChannelSenderImpl(std::unique_ptr<BlobCache> cache,
                         std::unique_ptr<Delegate> delegate);
   ~BlobChannelSenderImpl() override;
 
   // BlobChannelSender implementation.
+  std::vector<BlobChannelSender::CacheStateEntry> GetCachedBlobIds()
+      const override;
   void PutBlob(const BlobId& id, BlobDataPtr data) override;
   void DeliverBlob(const BlobId& id) override;
 
  private:
   std::unique_ptr<BlobCache> cache_;
   std::unique_ptr<Delegate> delegate_;
 
   // Used to track the item IDs in the receiver's cache. This may differ from
   // the set of IDs in |cache_|, for instance if an ID hasn't yet been
   // delivered, or has been evicted at the receiver.
   std::set<BlobId> receiver_cache_contents_;
 
   DISALLOW_COPY_AND_ASSIGN(BlobChannelSenderImpl);
 };
 
 }  // namespace blimp
 
 #endif  // BLIMP_NET_BLOB_CHANNEL_BLOB_CHANNEL_SENDER_IMPL_H_