Add support for testing content in SkyView

sky/engine/tonic/dart_state.h

Index: sky/engine/tonic/dart_state.h
diff --git a/sky/engine/tonic/dart_state.h b/sky/engine/tonic/dart_state.h
index 4562ce40e4f34781fe60a701672a586f48a9ab8c..87431cbbd5b05d20dab6f5d58d32c875ae2375dd 100644
--- a/sky/engine/tonic/dart_state.h
+++ b/sky/engine/tonic/dart_state.h
@@ -16,9 +16,10 @@
 #include "sky/engine/wtf/RefCounted.h"
 
 namespace blink {
-class DartStringCache;
 class DartClassLibrary;
 class DartExceptionFactory;
+class DartStringCache;
+class DartTimerHeap;
 
 // DartState represents the state associated with a given Dart isolate. The
 // lifetime of this object is controlled by the DartVM. If you want to hold a
@@ -54,12 +55,14 @@ class DartState : public base::SupportsUserData {
   DartClassLibrary& class_library() { return *class_library_; }
   DartStringCache& string_cache() { return *string_cache_; }
   DartExceptionFactory& exception_factory() { return *exception_factory_; }
+  DartTimerHeap& timer_heap() { return *timer_heap_; }
 
  private:
   Dart_Isolate isolate_;
   OwnPtr<DartClassLibrary> class_library_;
   OwnPtr<DartStringCache> string_cache_;
   OwnPtr<DartExceptionFactory> exception_factory_;
+  OwnPtr<DartTimerHeap> timer_heap_;
 
   base::WeakPtrFactory<DartState> weak_factory_;