Improve DartLoader error handling.

sky/engine/core/script/dart_loader.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 SKY_ENGINE_CORE_SCRIPT_DART_LOADER_H_
 #define SKY_ENGINE_CORE_SCRIPT_DART_LOADER_H_
 
 #include "base/callback_forward.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
@@ skipping 25 matching lines @@
 
   void WaitForDependencies(const HashSet<DartDependency*>& dependencies,
                            const base::Closure& callback);
 
   void set_dependency_catcher(DartDependencyCatcher* dependency_catcher) {
     DCHECK(!dependency_catcher_ || !dependency_catcher);
     dependency_catcher_ = dependency_catcher;
   }
 
   DartState* dart_state() const { return dart_state_.get(); }
+  bool saw_error() const { return saw_error_; }
 
  private:
   class Job;
   class ImportJob;
   class SourceJob;
   class DependencyWatcher;
   class WatcherSignaler;
 
   Dart_Handle Import(Dart_Handle library, Dart_Handle url);
   Dart_Handle Source(Dart_Handle library, Dart_Handle url);
   void DidCompleteImportJob(ImportJob* job, const Vector<uint8_t>& buffer);
   void DidCompleteSourceJob(SourceJob* job, const Vector<uint8_t>& buffer);
+  void DidFailJob(Job* job);
 
   base::WeakPtr<DartState> dart_state_;
   HashMap<String, Job*> pending_libraries_;
   HashSet<OwnPtr<Job>> jobs_;
   HashSet<OwnPtr<DependencyWatcher>> dependency_watchers_;
   DartDependencyCatcher* dependency_catcher_;
+  bool saw_error_;
 
   DISALLOW_COPY_AND_ASSIGN(DartLoader);
 };
 
 }  // namespace blink
 
 #endif  // SKY_ENGINE_CORE_SCRIPT_DART_LOADER_H_