[BlobAsync] Disk support for blob storage

storage/browser/blob/blob_async_builder_host.cc

 // Copyright 2015 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.
 
 #include "storage/browser/blob/blob_async_builder_host.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <memory>
 #include <utility>
 
 #include "base/bind.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/shared_memory.h"
 #include "storage/browser/blob/blob_data_handle.h"
+#include "storage/browser/blob/blob_memory_controller.h"
 #include "storage/browser/blob/blob_storage_context.h"
 
 namespace storage {
-namespace {
-
-bool CalculateBlobMemorySize(const std::vector<DataElement>& elements,
-                             size_t* shortcut_bytes,
-                             uint64_t* total_bytes) {
-  DCHECK(shortcut_bytes);
-  DCHECK(total_bytes);
-  base::CheckedNumeric<uint64_t> total_size_checked = 0;
-  base::CheckedNumeric<size_t> shortcut_size_checked = 0;
-  for (const auto& e : elements) {
-    if (e.type() == DataElement::TYPE_BYTES) {
-      total_size_checked += e.length();
-      shortcut_size_checked += e.length();
-    } else if (e.type() == DataElement::TYPE_BYTES_DESCRIPTION) {
-      total_size_checked += e.length();
-    } else {
-      continue;
-    }
-    if (!total_size_checked.IsValid() || !shortcut_size_checked.IsValid()) {
-      return false;
-    }
-  }
-  *shortcut_bytes = shortcut_size_checked.ValueOrDie();
-  *total_bytes = total_size_checked.ValueOrDie();
-  return true;
-}
-
-IPCBlobCreationCancelCode ConvertReferencedBlobErrorToConstructingError(
-    IPCBlobCreationCancelCode referenced_blob_error) {
-  switch (referenced_blob_error) {
-    // For most cases we propagate the error.
-    case IPCBlobCreationCancelCode::FILE_WRITE_FAILED:
-    case IPCBlobCreationCancelCode::SOURCE_DIED_IN_TRANSIT:
-    case IPCBlobCreationCancelCode::REFERENCED_BLOB_BROKEN:
-    case IPCBlobCreationCancelCode::OUT_OF_MEMORY:
-      return referenced_blob_error;
-    // Others we report that the referenced blob is broken, as we don't know
-    // why (the BLOB_DEREFERENCED_WHILE_BUILDING should never happen, as we hold
-    // onto the reference of the blobs we're using).
-    case IPCBlobCreationCancelCode::BLOB_DEREFERENCED_WHILE_BUILDING:
-      DCHECK(false) << "Referenced blob should never be dereferenced while we "
-                    << "are depending on it, as our system holds a handle.";
-    case IPCBlobCreationCancelCode::UNKNOWN:
-      return IPCBlobCreationCancelCode::REFERENCED_BLOB_BROKEN;
-  }
-  NOTREACHED();
-  return IPCBlobCreationCancelCode::REFERENCED_BLOB_BROKEN;
-}
-
-}  // namespace
-
+using MemoryStrategyResult = BlobMemoryController::MemoryStrategyResult;
 using MemoryItemRequest =
     BlobAsyncTransportRequestBuilder::RendererMemoryItemRequest;

[michaeln, 2016/07/07 20:05:22]

I think less nesting of structs and enum types might help readability,
MemoryItemRequest is a fine top level struct/class name.

[dmurph, 2016/07/11 23:33:26]

I consolidated all enums. I feel like keeping this one is fine, as it's only
used in this class and always directly ties to the request builder.

 
 BlobAsyncBuilderHost::BlobBuildingState::BlobBuildingState(
-    const std::string& uuid,
-    std::set<std::string> referenced_blob_uuids,
-    std::vector<std::unique_ptr<BlobDataHandle>>* referenced_blob_handles)
-    : data_builder(uuid),
-      referenced_blob_uuids(referenced_blob_uuids),
-      referenced_blob_handles(std::move(*referenced_blob_handles)) {}
+    const std::string& uuid)
+    : data_builder(uuid) {}
 
 BlobAsyncBuilderHost::BlobBuildingState::~BlobBuildingState() {}
 
 BlobAsyncBuilderHost::BlobAsyncBuilderHost() : ptr_factory_(this) {}
 
 BlobAsyncBuilderHost::~BlobAsyncBuilderHost() {}
 
-BlobTransportResult BlobAsyncBuilderHost::RegisterBlobUUID(
+BlobTransportResult BlobAsyncBuilderHost::RegisterBlob(
     const std::string& uuid,
     const std::string& content_type,
     const std::string& content_disposition,
-    const std::set<std::string>& referenced_blob_uuids,
-    BlobStorageContext* context) {
-  if (async_blob_map_.find(uuid) != async_blob_map_.end())
-    return BlobTransportResult::BAD_IPC;
-  if (referenced_blob_uuids.find(uuid) != referenced_blob_uuids.end())
-    return BlobTransportResult::BAD_IPC;
-  context->CreatePendingBlob(uuid, content_type, content_disposition);
-  std::vector<std::unique_ptr<BlobDataHandle>> handles;
-  for (const std::string& referenced_uuid : referenced_blob_uuids) {
-    std::unique_ptr<BlobDataHandle> handle =
-        context->GetBlobDataFromUUID(referenced_uuid);
-    if (!handle || handle->IsBroken()) {
-      // We cancel the blob right away, and don't bother storing our state.
-      context->CancelPendingBlob(
-          uuid, IPCBlobCreationCancelCode::REFERENCED_BLOB_BROKEN);
-      return BlobTransportResult::CANCEL_REFERENCED_BLOB_BROKEN;
-    }
-    handles.emplace_back(std::move(handle));
-  }
-  async_blob_map_[uuid] = base::WrapUnique(
-      new BlobBuildingState(uuid, referenced_blob_uuids, &handles));
-  return BlobTransportResult::DONE;
-}
+    const std::vector<DataElement>& elements,
+    BlobStorageContext* context,
+    std::unique_ptr<BlobDataHandle>* handle_output,
+    const RequestMemoryCallback& request_memory,
+    const ErrorCallback& report_error,
+    const DoneCallback& done_callback) {
+  DCHECK(context);
+  DCHECK(async_blob_map_.find(uuid) == async_blob_map_.end());
 
-BlobTransportResult BlobAsyncBuilderHost::StartBuildingBlob(
-    const std::string& uuid,
-    const std::vector<DataElement>& elements,
-    size_t memory_available,
-    BlobStorageContext* context,
-    const RequestMemoryCallback& request_memory) {
-  DCHECK(context);
-  DCHECK(async_blob_map_.find(uuid) != async_blob_map_.end());
-
-  // Step 1: Get the sizes.
-  size_t shortcut_memory_size_bytes = 0;
   uint64_t total_memory_size_bytes = 0;
-  if (!CalculateBlobMemorySize(elements, &shortcut_memory_size_bytes,
-                               &total_memory_size_bytes)) {
-    CancelBuildingBlob(uuid, IPCBlobCreationCancelCode::UNKNOWN, context);
+  MemoryStrategyResult memory_strategy;
+  if (!context->memory_controller_.DecideBlobTransportationMemoryStrategy(
+          elements, &total_memory_size_bytes, &memory_strategy)) {
     return BlobTransportResult::BAD_IPC;
   }
 
-  // Step 2: Check if we have enough memory to store the blob.
-  if (total_memory_size_bytes > memory_available) {
-    CancelBuildingBlob(uuid, IPCBlobCreationCancelCode::OUT_OF_MEMORY, context);
-    return BlobTransportResult::CANCEL_MEMORY_FULL;
-  }
-
-  // From here on, we know we can fit the blob in memory.
-  BlobBuildingState* state_ptr = async_blob_map_[uuid].get();
-  if (!state_ptr->request_builder.requests().empty()) {
-    // Check that we're not a duplicate call.
-    return BlobTransportResult::BAD_IPC;
-  }
-  state_ptr->request_memory_callback = request_memory;
-
-  // Step 3: Check to make sure the referenced blob information we received
-  //         earlier is correct:
+  // Validate that our referenced blobs.
   std::set<std::string> extracted_blob_uuids;

[kinuko, 2016/07/07 16:11:44]

not used

[dmurph, 2016/07/08 01:22:12]

Done.

   for (const DataElement& e : elements) {
     if (e.type() == DataElement::TYPE_BLOB) {
-      extracted_blob_uuids.insert(e.blob_uuid());
-      // We can't depend on ourselves.
       if (e.blob_uuid() == uuid) {
-        CancelBuildingBlob(uuid, IPCBlobCreationCancelCode::UNKNOWN, context);
         return BlobTransportResult::BAD_IPC;
       }
     }
   }
-  if (extracted_blob_uuids != state_ptr->referenced_blob_uuids) {
-    CancelBuildingBlob(uuid, IPCBlobCreationCancelCode::UNKNOWN, context);
-    return BlobTransportResult::BAD_IPC;
+
+  const BlobMemoryController& memory_controller = context->memory_controller();
+  std::unique_ptr<BlobBuildingState> state(new BlobBuildingState(uuid));
+  state->request_memory_callback = request_memory;
+
+  switch (memory_strategy) {
+    case MemoryStrategyResult::TOO_LARGE:
+      *handle_output =
+          context->BuildBrokenBlob(uuid, content_type, content_disposition,
+                                   IPCBlobCreationCancelCode::OUT_OF_MEMORY);
+      return BlobTransportResult::CANCEL_MEMORY_FULL;
+    case MemoryStrategyResult::SHORTCUT:
+    case MemoryStrategyResult::NONE_NEEDED: {
+      for (const DataElement& e : elements) {
+        DCHECK_NE(e.type(), DataElement::TYPE_BYTES_DESCRIPTION);
+        state->data_builder.AppendIPCDataElement(e);
+      }
+      *handle_output = context->BuildBlob(
+          state->data_builder, BlobStorageRegistry::BlobConstructedCallback());
+      return BlobTransportResult::DONE;
+    }
+    case MemoryStrategyResult::IPC:
+      state->strategy = IPCBlobItemRequestStrategy::IPC;
+      state->request_builder.InitializeForIPCRequests(
+          memory_controller.max_ipc_memory_size(), total_memory_size_bytes,
+          elements, &(state->data_builder));
+      break;
+    case MemoryStrategyResult::SHARED_MEMORY:
+      state->strategy = IPCBlobItemRequestStrategy::SHARED_MEMORY;
+      state->request_builder.InitializeForSharedMemoryRequests(
+          memory_controller.max_shared_memory_size(), total_memory_size_bytes,
+          elements, &(state->data_builder));
+      break;
+    case MemoryStrategyResult::FILE:
+      state->strategy = IPCBlobItemRequestStrategy::FILE;
+      state->request_builder.InitializeForFileRequests(
+          memory_controller.max_file_size(), total_memory_size_bytes, elements,
+          &(state->data_builder));
+      break;
+  }
+  // We initialize our requests received state now that they are populated.
+  state->request_received.resize(state->request_builder.requests().size(),
+                                 false);
+
+  BlobBuildingState* state_ptr = state.get();
+  async_blob_map_[uuid] = std::move(state);
+
+  if (memory_strategy == MemoryStrategyResult::FILE) {
+    LOG(ERROR) << "file!";
+    const auto& file_sizes = state_ptr->request_builder.file_sizes();
+    state_ptr->files.resize(file_sizes.size());
+    for (size_t i = 0; i < file_sizes.size(); i++) {
+      context->memory_controller_.CreateTemporaryFileForRenderer(
+          file_sizes[i], base::Bind(&BlobAsyncBuilderHost::OnFileCreated,
+                                    ptr_factory_.GetWeakPtr(), uuid, i));
+    }
+    *handle_output = context->BuildBlob(
+        state_ptr->data_builder,
+        base::Callback<void(bool, IPCBlobCreationCancelCode)>());

[michaeln, 2016/07/07 20:05:22]

this and line 81/82 should probably look alike

[dmurph, 2016/07/11 23:33:26]

Done.

+    return BlobTransportResult::PENDING_RESPONSES;
   }
 
-  // Step 4: Decide if we're using the shortcut method. This will also catch
-  //         the case where we don't have any memory items.
-  if (shortcut_memory_size_bytes == total_memory_size_bytes &&
-      shortcut_memory_size_bytes <= memory_available) {
-    for (const DataElement& e : elements) {
-      state_ptr->data_builder.AppendIPCDataElement(e);
+  state_ptr->request_memory_callback = request_memory;
+  state_ptr->error_callback = report_error;
+  state_ptr->done_callback = done_callback;
+
+  *handle_output = context->BuildBlob(
+      state_ptr->data_builder,
+      base::Bind(&BlobAsyncBuilderHost::OnCanStartBuildingBlob,
+                 ptr_factory_.GetWeakPtr(), uuid, context->AsWeakPtr()));
+
+  if ((*handle_output)->IsBroken()) {
+    switch ((*handle_output)->GetBrokenReason()) {
+      case IPCBlobCreationCancelCode::OUT_OF_MEMORY:
+        return BlobTransportResult::CANCEL_MEMORY_FULL;
+      case IPCBlobCreationCancelCode::REFERENCED_BLOB_BROKEN:
+        return BlobTransportResult::CANCEL_REFERENCED_BLOB_BROKEN;
+      // We don't handle the following cases as they can't happen during
+      // BlobStorageContext::BuildBlob.
+      case IPCBlobCreationCancelCode::UNKNOWN:
+      case IPCBlobCreationCancelCode::FILE_WRITE_FAILED:
+      case IPCBlobCreationCancelCode::SOURCE_DIED_IN_TRANSIT:
+      case IPCBlobCreationCancelCode::BLOB_DEREFERENCED_WHILE_BUILDING:
+        NOTREACHED();
     }
-    FinishBuildingBlob(state_ptr, context);
-    return BlobTransportResult::DONE;
+    return BlobTransportResult::CANCEL_UNKNOWN;
   }
-
-  // From here on, we know the blob's size is less than |memory_available|,
-  // so we know we're < max(size_t).
-  // Step 5: Decide if we're using shared memory.
-  if (total_memory_size_bytes > max_ipc_memory_size_) {
-    state_ptr->request_builder.InitializeForSharedMemoryRequests(
-        max_shared_memory_size_, total_memory_size_bytes, elements,
-        &(state_ptr->data_builder));
-  } else {
-    // Step 6: We can fit in IPC.
-    state_ptr->request_builder.InitializeForIPCRequests(
-        max_ipc_memory_size_, total_memory_size_bytes, elements,
-        &(state_ptr->data_builder));
-  }
-  // We initialize our requests received state now that they are populated.
-  state_ptr->request_received.resize(
-      state_ptr->request_builder.requests().size(), false);
-  return ContinueBlobMemoryRequests(uuid, context);
+  return BlobTransportResult::PENDING_RESPONSES;
 }
 
 BlobTransportResult BlobAsyncBuilderHost::OnMemoryResponses(
     const std::string& uuid,
     const std::vector<BlobItemBytesResponse>& responses,
     BlobStorageContext* context) {
   AsyncBlobMap::const_iterator state_it = async_blob_map_.find(uuid);
   if (state_it == async_blob_map_.end()) {
     DVLOG(1) << "Could not find blob " << uuid;
     return BlobTransportResult::BAD_IPC;
   }
   if (responses.empty()) {
     CancelBuildingBlob(uuid, IPCBlobCreationCancelCode::UNKNOWN, context);
     return BlobTransportResult::BAD_IPC;
   }
+
   BlobAsyncBuilderHost::BlobBuildingState* state = state_it->second.get();
-  BlobAsyncTransportRequestBuilder& request_builder = state->request_builder;
-  const auto& requests = request_builder.requests();
+  const auto& requests = state->request_builder.requests();
   for (const BlobItemBytesResponse& response : responses) {
     if (response.request_number >= requests.size()) {
       // Bad IPC, so we delete our record and ignore.
       DVLOG(1) << "Invalid request number " << response.request_number;
       CancelBuildingBlob(uuid, IPCBlobCreationCancelCode::UNKNOWN, context);
       return BlobTransportResult::BAD_IPC;
     }
     DCHECK_LT(response.request_number, state->request_received.size());
-    const MemoryItemRequest& request = requests[response.request_number];
     if (state->request_received[response.request_number]) {
       // Bad IPC, so we delete our record.
       DVLOG(1) << "Already received response for that request.";
       CancelBuildingBlob(uuid, IPCBlobCreationCancelCode::UNKNOWN, context);
       return BlobTransportResult::BAD_IPC;
     }
     state->request_received[response.request_number] = true;
-    bool invalid_ipc = false;
-    bool memory_error = false;
-    switch (request.message.transport_strategy) {
-      case IPCBlobItemRequestStrategy::IPC:
-        if (response.inline_data.size() < request.message.size) {
-          DVLOG(1) << "Invalid data size " << response.inline_data.size()
-                   << " vs requested size of " << request.message.size;
-          invalid_ipc = true;
-          break;
-        }
-        invalid_ipc = !state->data_builder.PopulateFutureData(
-            request.browser_item_index, &response.inline_data[0],
-            request.browser_item_offset, request.message.size);
-        break;
-      case IPCBlobItemRequestStrategy::SHARED_MEMORY:
-        if (state->num_shared_memory_requests == 0) {
-          DVLOG(1) << "Received too many responses for shared memory.";
-          invalid_ipc = true;
-          break;
-        }
-        state->num_shared_memory_requests--;
-        if (!state->shared_memory_block->memory()) {
-          // We just map the whole block, as we'll probably be accessing the
-          // whole thing in this group of responses. Another option is to use
-          // MapAt, remove the mapped boolean, and then exclude the
-          // handle_offset below.
-          size_t handle_size = request_builder.shared_memory_sizes()
-                                   [state->current_shared_memory_handle_index];
-          if (!state->shared_memory_block->Map(handle_size)) {
-            DVLOG(1) << "Unable to map memory to size " << handle_size;
-            memory_error = true;
-            break;
-          }
-        }
-
-        invalid_ipc = !state->data_builder.PopulateFutureData(
-            request.browser_item_index,
-            static_cast<const char*>(state->shared_memory_block->memory()) +
-                request.message.handle_offset,
-            request.browser_item_offset, request.message.size);
-        break;
-      case IPCBlobItemRequestStrategy::FILE:
-      case IPCBlobItemRequestStrategy::UNKNOWN:
-        DVLOG(1) << "Not implemented.";
-        invalid_ipc = true;
-        break;
-    }
-    if (invalid_ipc) {
-      // Bad IPC, so we delete our record and return false.
-      CancelBuildingBlob(uuid, IPCBlobCreationCancelCode::UNKNOWN, context);
+  }
+  switch (state->strategy) {
+    case IPCBlobItemRequestStrategy::IPC:
+      return OnIPCResponses(uuid, state, responses, context);
+    case IPCBlobItemRequestStrategy::SHARED_MEMORY:
+      return OnSharedMemoryResponses(uuid, state, responses, context);
+    case IPCBlobItemRequestStrategy::FILE:
+      return OnFileResponses(uuid, state, responses, context);
+    case IPCBlobItemRequestStrategy::UNKNOWN:
+      NOTREACHED();
       return BlobTransportResult::BAD_IPC;
-    }
-    if (memory_error) {
-      DVLOG(1) << "Shared memory error.";
-      CancelBuildingBlob(uuid, IPCBlobCreationCancelCode::OUT_OF_MEMORY,
-                         context);
-      return BlobTransportResult::CANCEL_MEMORY_FULL;
-    }
-    state->num_fulfilled_requests++;
   }
-  return ContinueBlobMemoryRequests(uuid, context);
 }
 
 void BlobAsyncBuilderHost::CancelBuildingBlob(const std::string& uuid,
                                               IPCBlobCreationCancelCode code,
                                               BlobStorageContext* context) {
   DCHECK(context);
   auto state_it = async_blob_map_.find(uuid);
   if (state_it == async_blob_map_.end()) {
     return;
   }
   // We can have the blob dereferenced by the renderer, but have it still being
   // 'built'. In this case, it's destructed in the context, but we still have
   // it in our map. Hence we make sure the context has the entry before
   // calling cancel.
-  if (context->registry().HasEntry(uuid))
-    context->CancelPendingBlob(uuid, code);
+  if (context->registry().HasEntry(uuid)) {
+    context->BreakAndFinishBlob(uuid, code);
+  }
   async_blob_map_.erase(state_it);
 }
 
 void BlobAsyncBuilderHost::CancelAll(BlobStorageContext* context) {
   DCHECK(context);
   // If the blob still exists in the context (and is being built), then we know
   // that someone else is expecting our blob, and we need to cancel it to let
   // the dependency know it's gone.
   std::vector<std::unique_ptr<BlobDataHandle>> referenced_pending_blobs;
   for (const auto& uuid_state_pair : async_blob_map_) {
     if (context->IsBeingBuilt(uuid_state_pair.first)) {
       referenced_pending_blobs.emplace_back(
           context->GetBlobDataFromUUID(uuid_state_pair.first));
     }
   }
   // We clear the map before canceling them to prevent any strange reentry into
   // our class (see ReferencedBlobFinished) if any blobs were waiting for others
   // to construct.
   async_blob_map_.clear();
   for (const std::unique_ptr<BlobDataHandle>& handle :
        referenced_pending_blobs) {
-    context->CancelPendingBlob(
+    context->BreakAndFinishBlob(
         handle->uuid(), IPCBlobCreationCancelCode::SOURCE_DIED_IN_TRANSIT);
   }
 }
 
-BlobTransportResult BlobAsyncBuilderHost::ContinueBlobMemoryRequests(
+BlobTransportResult BlobAsyncBuilderHost::StartRequests(
     const std::string& uuid,
+    BlobBuildingState* state,
     BlobStorageContext* context) {
+  switch (state->strategy) {
+    case IPCBlobItemRequestStrategy::IPC:
+      SendIPCRequests(state, context);
+      return BlobTransportResult::DONE;
+    case IPCBlobItemRequestStrategy::SHARED_MEMORY:
+      return ContinueSharedMemoryRequests(uuid, state, context);
+    case IPCBlobItemRequestStrategy::FILE:
+    case IPCBlobItemRequestStrategy::UNKNOWN:
+      NOTREACHED();
+      return BlobTransportResult::CANCEL_UNKNOWN;
+  }
+}
+
+void BlobAsyncBuilderHost::OnCanStartBuildingBlob(
+    const std::string& uuid,
+    base::WeakPtr<BlobStorageContext> context,
+    bool success,
+    IPCBlobCreationCancelCode reason) {

[michaeln, 2016/07/07 20:05:22]

where are |success| and |reason| used?

[dmurph, 2016/07/11 23:33:26]

Fixed in new patch.

+  LOG(ERROR) << "We can fit now!";
+  if (!context) {
+    async_blob_map_.erase(uuid);
+    return;
+  }
   AsyncBlobMap::const_iterator state_it = async_blob_map_.find(uuid);
-  DCHECK(state_it != async_blob_map_.end());
-  BlobAsyncBuilderHost::BlobBuildingState* state = state_it->second.get();
+  if (state_it == async_blob_map_.end()) {
+    return;
+  }
+  BlobBuildingState* state = state_it->second.get();
+  BlobTransportResult result = StartRequests(uuid, state, context.get());
+  if (result == BlobTransportResult::PENDING_RESPONSES)
+    return;
+  ErrorCallback error_callback = state->error_callback;
+  DoneCallback done_callback = state->done_callback;
+  async_blob_map_.erase(state_it);
+  switch (result) {
+    case BlobTransportResult::PENDING_RESPONSES:
+      NOTREACHED();
+    case BlobTransportResult::CANCEL_UNKNOWN:
+    case BlobTransportResult::BAD_IPC:
+      error_callback.Run(IPCBlobCreationCancelCode::UNKNOWN);
+      break;
+    case BlobTransportResult::CANCEL_MEMORY_FULL:
+      error_callback.Run(IPCBlobCreationCancelCode::OUT_OF_MEMORY);
+      break;
+    case BlobTransportResult::CANCEL_FILE_ERROR:
+      error_callback.Run(IPCBlobCreationCancelCode::FILE_WRITE_FAILED);
+      break;
+    case BlobTransportResult::CANCEL_REFERENCED_BLOB_BROKEN:
+      error_callback.Run(IPCBlobCreationCancelCode::REFERENCED_BLOB_BROKEN);
+      break;
+      return;
+    case BlobTransportResult::DONE:
+      done_callback.Run();
+      return;
+  }
+}
 
-  BlobAsyncTransportRequestBuilder& request_builder = state->request_builder;
-  const std::vector<MemoryItemRequest>& requests = request_builder.requests();
+void BlobAsyncBuilderHost::SendIPCRequests(BlobBuildingState* state,
+                                           BlobStorageContext* context) {
+  const std::vector<MemoryItemRequest>& requests =
+      state->request_builder.requests();
+  std::unique_ptr<std::vector<BlobItemBytesRequest>> byte_requests(
+      new std::vector<BlobItemBytesRequest>());
+
+  DCHECK(!requests.empty());
+  for (const MemoryItemRequest& request : requests) {
+    byte_requests->push_back(request.message);
+  }
+
+  state->request_memory_callback.Run(
+      std::move(byte_requests),
+      base::WrapUnique(new std::vector<base::SharedMemoryHandle>()),
+      base::WrapUnique(new std::vector<base::File>()));
+}
+
+BlobTransportResult BlobAsyncBuilderHost::OnIPCResponses(
+    const std::string& uuid,
+    BlobBuildingState* state,
+    const std::vector<BlobItemBytesResponse>& responses,
+    BlobStorageContext* context) {
+  const auto& requests = state->request_builder.requests();
   size_t num_requests = requests.size();
+  for (const BlobItemBytesResponse& response : responses) {
+    const MemoryItemRequest& request = requests[response.request_number];
+    if (response.inline_data.size() < request.message.size) {
+      DVLOG(1) << "Invalid data size " << response.inline_data.size()
+               << " vs requested size of " << request.message.size;
+      CancelBuildingBlob(uuid, IPCBlobCreationCancelCode::UNKNOWN, context);
+      return BlobTransportResult::BAD_IPC;
+      break;
+    }
+    bool success = state->data_builder.PopulateFutureData(
+        request.browser_item_index, &response.inline_data[0],
+        request.browser_item_offset, request.message.size);
+    if (!success) {
+      CancelBuildingBlob(uuid, IPCBlobCreationCancelCode::UNKNOWN, context);
+      return BlobTransportResult::BAD_IPC;
+    }
+    state->num_fulfilled_requests++;
+  }
   if (state->num_fulfilled_requests == num_requests) {
     FinishBuildingBlob(state, context);
     return BlobTransportResult::DONE;
   }
+  return BlobTransportResult::PENDING_RESPONSES;
+}
+
+BlobTransportResult BlobAsyncBuilderHost::ContinueSharedMemoryRequests(
+    const std::string& uuid,
+    BlobBuildingState* state,
+    BlobStorageContext* context) {
+  BlobAsyncTransportRequestBuilder& request_builder = state->request_builder;
+  const std::vector<MemoryItemRequest>& requests = request_builder.requests();
+  size_t num_requests = requests.size();
   DCHECK_LT(state->num_fulfilled_requests, num_requests);
   if (state->next_request == num_requests) {
     // We are still waiting on other requests to come back.
     return BlobTransportResult::PENDING_RESPONSES;
   }
 
   std::unique_ptr<std::vector<BlobItemBytesRequest>> byte_requests(
       new std::vector<BlobItemBytesRequest>());
   std::unique_ptr<std::vector<base::SharedMemoryHandle>> shared_memory(
       new std::vector<base::SharedMemoryHandle>());
 
   for (; state->next_request < num_requests; ++state->next_request) {
     const MemoryItemRequest& request = requests[state->next_request];
-
-    bool stop_accumulating = false;
     bool using_shared_memory_handle = state->num_shared_memory_requests > 0;
-    switch (request.message.transport_strategy) {
-      case IPCBlobItemRequestStrategy::IPC:
-        byte_requests->push_back(request.message);
-        break;
-      case IPCBlobItemRequestStrategy::SHARED_MEMORY:
-        if (using_shared_memory_handle &&
-            state->current_shared_memory_handle_index !=
-                request.message.handle_index) {
-          // We only want one shared memory per requesting blob.
-          stop_accumulating = true;
-          break;
-        }
-        using_shared_memory_handle = true;
-        state->current_shared_memory_handle_index =
-            request.message.handle_index;
-        state->num_shared_memory_requests++;
-
-        if (!state->shared_memory_block) {
-          state->shared_memory_block.reset(new base::SharedMemory());
-          size_t size =
-              request_builder
-                  .shared_memory_sizes()[request.message.handle_index];
-          if (!state->shared_memory_block->CreateAnonymous(size)) {
-            DVLOG(1) << "Unable to allocate shared memory for blob transfer.";
-            return BlobTransportResult::CANCEL_MEMORY_FULL;
-          }
-        }
-        shared_memory->push_back(state->shared_memory_block->handle());
-        byte_requests->push_back(request.message);
-        // Since we are only using one handle at a time, transform our handle
-        // index correctly back to 0.
-        byte_requests->back().handle_index = 0;
-        break;
-      case IPCBlobItemRequestStrategy::FILE:
-      case IPCBlobItemRequestStrategy::UNKNOWN:
-        NOTREACHED() << "Not implemented yet.";
-        break;
-    }
-    if (stop_accumulating) {
+    if (using_shared_memory_handle &&
+        state->current_shared_memory_handle_index !=
+            request.message.handle_index) {
+      // We only want one shared memory per requesting blob.
       break;
     }
+    state->current_shared_memory_handle_index = request.message.handle_index;
+    state->num_shared_memory_requests++;
+
+    if (!state->shared_memory_block) {
+      state->shared_memory_block.reset(new base::SharedMemory());
+      size_t size =
+          request_builder.shared_memory_sizes()[request.message.handle_index];
+      if (!state->shared_memory_block->CreateAnonymous(size)) {
+        DVLOG(1) << "Unable to allocate shared memory for blob transfer.";
+        return BlobTransportResult::CANCEL_MEMORY_FULL;
+      }
+    }
+    shared_memory->push_back(state->shared_memory_block->handle());
+    byte_requests->push_back(request.message);
+    // Since we are only using one handle at a time, transform our handle
+    // index correctly back to 0.
+    byte_requests->back().handle_index = 0;
   }
   DCHECK(!requests.empty());
 
   state->request_memory_callback.Run(
       std::move(byte_requests), std::move(shared_memory),
       base::WrapUnique(new std::vector<base::File>()));
   return BlobTransportResult::PENDING_RESPONSES;
 }
 
-void BlobAsyncBuilderHost::ReferencedBlobFinished(
-    const std::string& owning_blob_uuid,
-    base::WeakPtr<BlobStorageContext> context,
-    bool construction_success,
-    IPCBlobCreationCancelCode reason) {
-  if (!context) {
-    return;
+BlobTransportResult BlobAsyncBuilderHost::OnSharedMemoryResponses(
+    const std::string& uuid,
+    BlobBuildingState* state,
+    const std::vector<BlobItemBytesResponse>& responses,
+    BlobStorageContext* context) {
+  BlobAsyncTransportRequestBuilder& request_builder = state->request_builder;
+  const auto& requests = request_builder.requests();
+  for (const BlobItemBytesResponse& response : responses) {
+    const MemoryItemRequest& request = requests[response.request_number];
+    if (state->num_shared_memory_requests == 0) {
+      DVLOG(1) << "Received too many responses for shared memory.";
+      CancelBuildingBlob(uuid, IPCBlobCreationCancelCode::UNKNOWN, context);
+      return BlobTransportResult::BAD_IPC;
+      break;
+    }
+    state->num_shared_memory_requests--;
+    if (!state->shared_memory_block->memory()) {
+      // We just map the whole block, as we'll probably be accessing the
+      // whole thing in this group of responses. Another option is to use
+      // MapAt, remove the mapped boolean, and then exclude the
+      // handle_offset below.
+      size_t handle_size =
+          request_builder
+              .shared_memory_sizes()[state->current_shared_memory_handle_index];
+      if (!state->shared_memory_block->Map(handle_size)) {
+        DVLOG(1) << "Unable to map memory to size " << handle_size;
+        CancelBuildingBlob(uuid, IPCBlobCreationCancelCode::OUT_OF_MEMORY,
+                           context);
+        return BlobTransportResult::CANCEL_MEMORY_FULL;
+      }
+    }
+
+    bool success = state->data_builder.PopulateFutureData(
+        request.browser_item_index,
+        static_cast<const char*>(state->shared_memory_block->memory()) +
+            request.message.handle_offset,
+        request.browser_item_offset, request.message.size);
+
+    if (!success) {
+      CancelBuildingBlob(uuid, IPCBlobCreationCancelCode::UNKNOWN, context);
+      return BlobTransportResult::BAD_IPC;
+    }
+    state->num_fulfilled_requests++;
   }
-  auto state_it = async_blob_map_.find(owning_blob_uuid);
+  if (state->num_fulfilled_requests == requests.size()) {
+    FinishBuildingBlob(state, context);
+    return BlobTransportResult::DONE;
+  }
+  return ContinueSharedMemoryRequests(uuid, state, context);
+}
+
+void BlobAsyncBuilderHost::OnFileCreated(
+    const std::string& uuid,
+    size_t handle_index,
+    BlobMemoryController::FileCreationInfo file_info) {
+  LOG(ERROR) << "File crated!";
+  AsyncBlobMap::const_iterator state_it = async_blob_map_.find(uuid);
   if (state_it == async_blob_map_.end()) {
     return;
   }
-  if (!construction_success) {
-    CancelBuildingBlob(owning_blob_uuid,
-                       ConvertReferencedBlobErrorToConstructingError(reason),
-                       context.get());
-    return;
+  BlobBuildingState* state = state_it->second.get();
+  DCHECK_LT(handle_index, state->files.size());
+  state->files[handle_index] = std::move(file_info.file_reference);
+
+  const BlobAsyncTransportRequestBuilder& request_builder =
+      state->request_builder;
+  const std::vector<MemoryItemRequest>& requests = request_builder.requests();
+
+  std::unique_ptr<std::vector<BlobItemBytesRequest>> byte_requests(
+      new std::vector<BlobItemBytesRequest>());
+
+  std::unique_ptr<std::vector<base::File>> files(new std::vector<base::File>());
+  files->push_back(std::move(file_info.file.value()));
+  file_info.file = base::nullopt;
+
+  for (const MemoryItemRequest& request : requests) {
+    if (request.message.handle_index != handle_index) {
+      continue;
+    }
+    byte_requests->push_back(request.message);
+    byte_requests->back().handle_index = 0;
   }
-  BlobBuildingState* state = state_it->second.get();
-  DCHECK_GT(state->num_referenced_blobs_building, 0u);
-  if (--state->num_referenced_blobs_building == 0) {
-    context->CompletePendingBlob(state->data_builder);
-    async_blob_map_.erase(state->data_builder.uuid());
+
+  state->request_memory_callback.Run(
+      std::move(byte_requests),
+      base::WrapUnique(new std::vector<base::SharedMemoryHandle>()),
+      std::move(files));
+}
+
+BlobTransportResult BlobAsyncBuilderHost::OnFileResponses(
+    const std::string& uuid,
+    BlobBuildingState* state,
+    const std::vector<BlobItemBytesResponse>& responses,
+    BlobStorageContext* context) {
+  BlobAsyncTransportRequestBuilder& request_builder = state->request_builder;
+  const auto& requests = request_builder.requests();
+  for (const BlobItemBytesResponse& response : responses) {
+    const MemoryItemRequest& request = requests[response.request_number];
+    const scoped_refptr<ShareableFileReference>& file_ref =
+        state->files[request.message.handle_index];
+    bool success = state->data_builder.PopulateFutureFile(
+        request.browser_item_index, file_ref, response.time_file_modified);
+    if (!success) {
+      CancelBuildingBlob(uuid, IPCBlobCreationCancelCode::UNKNOWN, context);
+      return BlobTransportResult::BAD_IPC;
+    }
+    state->num_fulfilled_requests++;
   }
+  if (state->num_fulfilled_requests == requests.size()) {
+    FinishBuildingBlob(state, context);
+    return BlobTransportResult::DONE;
+  }
+  return BlobTransportResult::PENDING_RESPONSES;
 }
 
 void BlobAsyncBuilderHost::FinishBuildingBlob(BlobBuildingState* state,
                                               BlobStorageContext* context) {
-  if (!state->referenced_blob_uuids.empty()) {
-    DCHECK_EQ(0u, state->num_referenced_blobs_building);
-    state->num_referenced_blobs_building = 0;
-    // We assume re-entry is not possible, as RunOnConstructionComplete
-    // will schedule a task when the blob is being built. Thus we can't have the
-    // case where |num_referenced_blobs_building| reaches 0 in the
-    // ReferencedBlobFinished method before we're finished looping.
-    for (const std::string& referenced_uuid : state->referenced_blob_uuids) {
-      if (context->IsBeingBuilt(referenced_uuid)) {
-        state->num_referenced_blobs_building++;
-        context->RunOnConstructionComplete(
-            referenced_uuid,
-            base::Bind(&BlobAsyncBuilderHost::ReferencedBlobFinished,
-                       ptr_factory_.GetWeakPtr(), state->data_builder.uuid(),
-                       context->AsWeakPtr()));
-      }
-    }
-    if (state->num_referenced_blobs_building > 0) {
-      // We wait until referenced blobs are done.
-      return;
-    }
-  }
-  context->CompletePendingBlob(state->data_builder);
+  context->FinishedPopulatingBlob(state->data_builder.uuid());
   async_blob_map_.erase(state->data_builder.uuid());
 }
 
 }  // namespace storage