Use the tonic namespace for tonic + resulting build fixes

tonic/dart_persistent_value.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_TONIC_DART_PERSISTENT_VALUE_H_
 #define SKY_ENGINE_TONIC_DART_PERSISTENT_VALUE_H_
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "dart/runtime/include/dart_api.h"
 
-namespace blink {
+namespace tonic {
 class DartState;
 
 // DartPersistentValue is a bookkeeping class to help pair calls to
 // Dart_NewPersistentHandle with Dart_DeletePersistentHandle. Consider using
 // this class instead of holding a Dart_PersistentHandle directly so that you
 // don't leak the Dart_PersistentHandle.
 class DartPersistentValue {
  public:
   DartPersistentValue();
   DartPersistentValue(DartState* dart_state, Dart_Handle value);
   ~DartPersistentValue();
 
   Dart_PersistentHandle value() const { return value_; }
   bool is_empty() const { return !value_; }
 
   void Set(DartState* dart_state, Dart_Handle value);
   void Clear();
   Dart_Handle Release();
 
   const base::WeakPtr<DartState>& dart_state() const { return dart_state_; }
 
  private:
   base::WeakPtr<DartState> dart_state_;
   Dart_PersistentHandle value_;
 
   DISALLOW_COPY_AND_ASSIGN(DartPersistentValue);
 };
 
-}  // namespace blink
+}  // namespace tonic
 
 #endif  // SKY_ENGINE_TONIC_DART_PERSISTENT_VALUE_H_