Incorporate BlobChannel into Blimp image encode/decode pipeline.

blimp/client/feature/compositor/blob_image_serialization_processor.h

Index: blimp/client/feature/compositor/blob_image_serialization_processor.h
diff --git a/blimp/client/feature/compositor/blob_image_serialization_processor.h b/blimp/client/feature/compositor/blob_image_serialization_processor.h
new file mode 100644
index 0000000000000000000000000000000000000000..deb1ddb1bbe89989b3830e22e756167887c093e0
--- /dev/null
+++ b/blimp/client/feature/compositor/blob_image_serialization_processor.h
@@ -0,0 +1,79 @@
+// 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_CLIENT_FEATURE_COMPOSITOR_BLOB_IMAGE_SERIALIZATION_PROCESSOR_H_
+#define BLIMP_CLIENT_FEATURE_COMPOSITOR_BLOB_IMAGE_SERIALIZATION_PROCESSOR_H_
+
+#include <memory>
+
+#include "base/macros.h"
+#include "base/memory/singleton.h"
+#include "cc/proto/image_serialization_processor.h"
+#include "third_party/skia/include/core/SkPicture.h"
+
+class SkPixelSerializer;
+
+namespace blimp {
+
+class BlobChannelReceiver;
+
+namespace client {
+
+// Adds BlobChannel image retrieval support to the Skia image decoding process.
+class BlobImageSerializationProcessor : public cc::ImageSerializationProcessor {
+ public:
+  class ErrorDelegate {
+   public:
+    virtual void OnImageDecodeError() = 0;
+  };
+
+  static BlobImageSerializationProcessor* current();

[Wez, 2016/06/10 22:29:54]

nit: Brief comment to summarize that this returns a globally-allocated instance
that the caller must have created with an appropriate lifetime (are there any
threading constraints here, too?)

[Kevin M, 2016/06/10 23:51:50]

Done. No threading constraints - this class is meant to be callable from a
number of raster threads - the cache manages concurrent access w/a lock. I made
GetAndDecodeBlob() const to ensure that no object state can change.

+
+  BlobImageSerializationProcessor();
+  virtual ~BlobImageSerializationProcessor();
+
+  // Sets the |blob_receiver| to use for reading images.
+  // |blob_receiver| must outlive |this|.
+  void set_blob_receiver(BlobChannelReceiver* blob_receiver) {
+    blob_receiver_ = blob_receiver;
+  }
+
+  // |error_delegate| must outlive this.
+  void set_error_delegate(ErrorDelegate* error_delegate) {
+    error_delegate_ = error_delegate;
+  }
+
+  // Retrieves a bitmap with ID |input| from |blob_receiver_| and decodes it
+  // to |bitmap|.
+  bool GetAndDecodeBlob(const void* input, size_t input_size, SkBitmap* bitmap);
+
+ private:
+  friend struct base::DefaultSingletonTraits<BlobImageSerializationProcessor>;
+
+  // Adapts a bare function pointer call to a singleton call to
+  // GetAndDecodeBlob().

[Wez, 2016/06/10 22:29:54]

nit: Suggest "to a GetAndDecodeBlob() call on the current processor." or
similar.

[Kevin M, 2016/06/10 23:51:50]

Done.

+  static bool InstallPixelRefProc(const void* input,
+                                  size_t input_size,
+                                  SkBitmap* bitmap);
+
+  // cc:ImageSerializationProcessor implementation.
+  SkPixelSerializer* GetPixelSerializer() override;
+  SkPicture::InstallPixelRefProc GetPixelDeserializer() override;
+
+  // Interface for accessing stored images received over the Blob Channel.
+  BlobChannelReceiver* blob_receiver_ = nullptr;
+
+  ErrorDelegate* error_delegate_ = nullptr;
+
+  // Pointer is bound on object construction, and set to nullptr on object
+  // deletion. Only one BlobImageSerializationProcessor may live at a time.

[Wez, 2016/06/10 22:29:54]

nit: "be live" would read more naturally that "live"?

[Kevin M, 2016/06/10 23:51:50]

I had to read that in my head a few times phonetically before that made sense.
Dumb English language, arrr!

+  static BlobImageSerializationProcessor* current_instance_;
+
+  DISALLOW_COPY_AND_ASSIGN(BlobImageSerializationProcessor);
+};
+
+}  // namespace client
+}  // namespace blimp
+
+#endif  // BLIMP_CLIENT_FEATURE_COMPOSITOR_BLOB_IMAGE_SERIALIZATION_PROCESSOR_H_