Split Resource::Status into a separate file

This is to remove dependencies from ImageResourceInfo.h and
ImageResourceContent.h to Resource.h in
https://codereview.chromium.org/2469873002/.

BUG=667641

Review-Url: https://codereview.chromium.org/2537063002
Cr-Commit-Position: refs/heads/master@{#437700}

third_party/WebKit/Source/core/fetch/BUILD.gn

@@ -41,6 +41,7 @@ blink_core_sources("fetch") {
     "ResourceLoader.h",
     "ResourceLoaderOptions.h",
     "ResourceLoadingLog.h",
+    "ResourceStatus.h",
     "SubstituteData.h",
     "UniqueIdentifier.cpp",
     "UniqueIdentifier.h",

third_party/WebKit/Source/core/fetch/Resource.cpp

@@ -301,6 +301,12 @@ void Resource::ResourceCallback::runTask() {
     resource->finishPendingClients();
 }
 
+constexpr Resource::Status Resource::NotStarted;
+constexpr Resource::Status Resource::Pending;
+constexpr Resource::Status Resource::Cached;
+constexpr Resource::Status Resource::LoadError;
+constexpr Resource::Status Resource::DecodeError;
+
 Resource::Resource(const ResourceRequest& request,
                    Type type,
                    const ResourceLoaderOptions& options)

third_party/WebKit/Source/core/fetch/Resource.h

@@ -28,6 +28,7 @@
 #include "core/fetch/CachedMetadataHandler.h"
 #include "core/fetch/IntegrityMetadata.h"
 #include "core/fetch/ResourceLoaderOptions.h"
+#include "core/fetch/ResourceStatus.h"
 #include "platform/MemoryCoordinator.h"
 #include "platform/SharedBuffer.h"
 #include "platform/Timer.h"
@@ -83,13 +84,14 @@ class CORE_EXPORT Resource : public GarbageCollectedFinalized<Resource>,
   };
   static const int kLastResourceType = Manifest + 1;
 
-  enum Status {
-    NotStarted,
-    Pending,  // load in progress
-    Cached,   // load completed successfully
-    LoadError,
-    DecodeError
-  };
+  using Status = ResourceStatus;
+
+  // TODO(hiroshige): Remove the following declarations.
+  static constexpr Status NotStarted = ResourceStatus::NotStarted;
+  static constexpr Status Pending = ResourceStatus::Pending;
+  static constexpr Status Cached = ResourceStatus::Cached;
+  static constexpr Status LoadError = ResourceStatus::LoadError;
+  static constexpr Status DecodeError = ResourceStatus::DecodeError;
 
   // Whether a resource client for a preload should mark the preload as
   // referenced.

third_party/WebKit/Source/core/fetch/ResourceStatus.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 ResourceStatus_h
+#define ResourceStatus_h
+
+namespace blink {
+
+enum class ResourceStatus {
+  NotStarted,
+  Pending,  // load in progress
+  Cached,   // load completed successfully
+  LoadError,
+  DecodeError
+};
+
+}  // namespace blink
+
+#endif