Make it possible to run Sky apps offline

sky/shell/dart/dart_library_provider_files.cc

Index: sky/shell/dart/dart_library_provider_files.cc
diff --git a/sky/shell/dart/dart_library_provider_files.cc b/sky/shell/dart/dart_library_provider_files.cc
new file mode 100644
index 0000000000000000000000000000000000000000..04a6284f17557d2a7e73aa1c79f2b5b17f675851
--- /dev/null
+++ b/sky/shell/dart/dart_library_provider_files.cc
@@ -0,0 +1,78 @@
+// 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 "sky/shell/dart/dart_library_provider_files.h"
+
+#include "base/bind.h"
+#include "base/strings/string_util.h"
+#include "base/threading/worker_pool.h"
+#include "mojo/common/data_pipe_utils.h"
+#include "sky/engine/tonic/dart_converter.h"
+
+namespace sky {
+namespace shell {
+namespace {
+
+void Ignored(bool) {
+}
+
+base::FilePath SimplifyPath(const base::FilePath& path) {
+  std::vector<base::FilePath::StringType> components;
+  path.GetComponents(&components);
+  base::FilePath result;
+  for (const auto& component : components) {
+    if (component == base::FilePath::kCurrentDirectory)
+      continue;
+    if (component == base::FilePath::kParentDirectory)
+      result = result.DirName();
+    else
+      result = result.Append(component);
+  }
+  return result;
+}
+
+}  // namespace
+
+DartLibraryProviderFiles::DartLibraryProviderFiles(
+    const base::FilePath& package_root)
+    : package_root_(package_root) {
+}
+
+DartLibraryProviderFiles::~DartLibraryProviderFiles() {
+}
+
+void DartLibraryProviderFiles::GetLibraryAsStream(
+    const String& name,
+    blink::DataPipeConsumerCallback callback) {
+  mojo::DataPipe pipe;
+  callback.Run(pipe.consumer_handle.Pass());
+
+  base::FilePath source(name.toUTF8());
+  scoped_refptr<base::TaskRunner> runner =
+      base::WorkerPool::GetTaskRunner(true);
+  mojo::common::CopyFromFile(source, pipe.producer_handle.Pass(), 0,
+                             runner.get(), base::Bind(&Ignored));
+}
+
+std::string DartLibraryProviderFiles::CanonicalizePackageURL(std::string url) {
+  DCHECK(StartsWithASCII(url, "package:", true));
+  ReplaceFirstSubstringAfterOffset(&url, 0, "package:", "");
+  return package_root_.Append(url).AsUTF8Unsafe();
+}
+
+Dart_Handle DartLibraryProviderFiles::CanonicalizeURL(Dart_Handle library,
+                                                      Dart_Handle url) {
+  std::string string = blink::StdStringFromDart(url);
+  if (StartsWithASCII(string, "dart:", true))
+    return url;
+  if (StartsWithASCII(string, "package:", true))
+    return blink::StdStringToDart(CanonicalizePackageURL(string));
+  base::FilePath base_path(blink::StdStringFromDart(Dart_LibraryUrl(library)));
+  base::FilePath resolved_path = base_path.DirName().Append(string);
+  base::FilePath normalized_path = SimplifyPath(resolved_path);
+  return blink::StdStringToDart(normalized_path.AsUTF8Unsafe());
+}
+
+}  // namespace shell
+}  // namespace sky