[BlobAsync] Disk support for blob storage

storage/common/blob_storage/blob_storage_constants.h

 // 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.
 
 #ifndef STORAGE_COMMON_BLOB_STORAGE_BLOB_STORAGE_CONSTANTS_H_
 #define STORAGE_COMMON_BLOB_STORAGE_BLOB_STORAGE_CONSTANTS_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
+#include "base/callback_forward.h"
+#include "storage/common/storage_common_export.h"
+
 namespace storage {
 
 // TODO(michaeln): use base::SysInfo::AmountOfPhysicalMemoryMB() in some
 // way to come up with a better limit.
 const int64_t kBlobStorageMaxMemoryUsage = 500 * 1024 * 1024;  // Half a gig.
 const size_t kBlobStorageIPCThresholdBytes = 250 * 1024;
 const size_t kBlobStorageMaxSharedMemoryBytes = 10 * 1024 * 1024;
 const uint64_t kBlobStorageMaxFileSizeBytes = 100 * 1024 * 1024;
-const uint64_t kBlobStorageMinFileSizeBytes = 1 * 1024 * 1024;
+const uint64_t kBlobStorageMinFileSizeBytes = 5 * 1024 * 1024;
 const size_t kBlobStorageMaxBlobMemorySize =
     kBlobStorageMaxMemoryUsage - kBlobStorageMinFileSizeBytes;
+const uint64_t kBlobStorageInFlightMemory = kBlobStorageMinFileSizeBytes;
+const uint64_t kBlobStorageMaxDiskSpace = 5ull * 1024 * 1024 * 1024;  // 5 gigs.
 
 enum class IPCBlobItemRequestStrategy {
   UNKNOWN = 0,
   IPC,
   SHARED_MEMORY,
   FILE,
   LAST = FILE
 };
 
-// These items cannot be reordered or renumbered because they're recorded to
-// UMA. New items must be added immediately before LAST, and LAST must be set to
-// the the last item.
-enum class IPCBlobCreationCancelCode {
-  UNKNOWN = 0,
+// This is the enum to rule them all in the blob system.
+// These values are used in UMA metrics, so they should not be changed. Please
+// update LAST_ERROR if you add an error condition and LAST if you add new
+// state.
+enum class BlobStatus {
+  // Error case section:
+  // The construction arguments are invalid.
+  INVALID_CONSTRUCTION_ARGUMENTS = 0,
+  // We don't have enough memory for the blob.
   OUT_OF_MEMORY = 1,
   // We couldn't create or write to a file. File system error, like a full disk.
   FILE_WRITE_FAILED = 2,
   // The renderer was destroyed while data was in transit.
   SOURCE_DIED_IN_TRANSIT = 3,
   // The renderer destructed the blob before it was done transferring, and there
   // were no outstanding references (no one is waiting to read) to keep the
   // blob alive.
   BLOB_DEREFERENCED_WHILE_BUILDING = 4,
   // A blob that we referenced during construction is broken, or a browser-side
   // builder tries to build a blob with a blob reference that isn't finished
   // constructing.
   REFERENCED_BLOB_BROKEN = 5,
-  LAST = REFERENCED_BLOB_BROKEN
+  LAST_ERROR = REFERENCED_BLOB_BROKEN,
+
+  // Blob state section:
+  // The blob is finished constructing.
+  DONE = 200,
+  // The system is pending on disk, memory availability, or construction in
+  // general.
+  PENDING = 201,
+  LAST = PENDING
 };
 
+using BlobStatusCallback = base::Callback<void(BlobStatus)>;
+
+// Returns if the status is an error code.
+STORAGE_COMMON_EXPORT bool BlobStatusIsError(BlobStatus status);
+
+// Returns if the status is an error code.
+STORAGE_COMMON_EXPORT bool BlobStatusIsBadIPC(BlobStatus status);
+
 }  // namespace storage
 
 #endif  // STORAGE_COMMON_BLOB_STORAGE_BLOB_STORAGE_CONSTANTS_H_