Blimp: Add BlobChannel Helium messages and delegate impls.

blimp/net/blob_channel/blob_channel_receiver.h

Index: blimp/net/blob_channel/blob_channel_receiver.h
diff --git a/blimp/net/blob_channel/blob_channel_receiver.h b/blimp/net/blob_channel/blob_channel_receiver.h
index bdfcd236bd62e5a58da2c0d41f1fe0cc1592b75e..4fd189cdf2445feaf5706fd17a32683d58209233 100644
--- a/blimp/net/blob_channel/blob_channel_receiver.h
+++ b/blimp/net/blob_channel/blob_channel_receiver.h
@@ -16,7 +16,6 @@ namespace blimp {
 
 class BlobCache;
 
-// Receives blobs from a remote sender.
 class BLIMP_NET_EXPORT BlobChannelReceiver {
  public:
   class Delegate {
@@ -24,44 +23,51 @@ class BLIMP_NET_EXPORT BlobChannelReceiver {
     Delegate();
     virtual ~Delegate();
 
+    // Sets the Receiver object which will take incoming blobs.
+    void SetReceiver(BlobChannelReceiver* receiver);
+
    protected:
     // Forwards incoming blob data to |receiver_|.
     void OnBlobReceived(const BlobId& id, BlobDataPtr data);
 
    private:
-    friend class BlobChannelReceiver;
-
-    // Sets the Receiver object which will take incoming blobs.
-    void SetReceiver(BlobChannelReceiver* receiver);
-
     BlobChannelReceiver* receiver_ = nullptr;
 
     DISALLOW_COPY_AND_ASSIGN(Delegate);
   };
 
-  BlobChannelReceiver(std::unique_ptr<BlobCache> cache,
-                      std::unique_ptr<Delegate> delegate);
-  ~BlobChannelReceiver();
+  BlobChannelReceiver();
+  virtual ~BlobChannelReceiver();
 
   // Gets a blob from the BlobChannel.
   // Returns nullptr if the blob is not available in the channel.
   // Can be accessed concurrently from any thread. Calling code must ensure that
   // the object instance outlives all calls to Get().
-  BlobDataPtr Get(const BlobId& id);
-
- private:
-  friend class Delegate;
+  virtual BlobDataPtr Get(const BlobId& id) = 0;
 
   // Called by Delegate::OnBlobReceived() when a blob arrives over the channel.
-  void OnBlobReceived(const BlobId& id, BlobDataPtr data);
+  virtual void OnBlobReceived(const BlobId& id, BlobDataPtr data) = 0;
+};
+
+// Receives blobs from a remote sender.
+class BLIMP_NET_EXPORT BlobChannelReceiverImpl : public BlobChannelReceiver {

[haibinlu, 2016/05/12 18:20:09]

shall this be in blob_channel_receiver_impl.h?

[Kevin M, 2016/05/13 18:40:24]

IMO it's not necessary - in practice, there will only be one non-test impl
class. The interface separation is there only for the benefit of test code.

+ public:
+  BlobChannelReceiverImpl(std::unique_ptr<BlobCache> cache,
+                          std::unique_ptr<Delegate> delegate);
+  ~BlobChannelReceiverImpl() override;
 
+  // BlobChannelReceiver implementation.
+  BlobDataPtr Get(const BlobId& id) override;
+  void OnBlobReceived(const BlobId& id, BlobDataPtr data) override;
+
+ private:
   std::unique_ptr<BlobCache> cache_;
   std::unique_ptr<Delegate> delegate_;
 
   // Guards against concurrent access to |cache_|.
   base::Lock cache_lock_;
 
-  DISALLOW_COPY_AND_ASSIGN(BlobChannelReceiver);
+  DISALLOW_COPY_AND_ASSIGN(BlobChannelReceiverImpl);
 };
 
 }  // namespace blimp