Add ContextLifecycleObserver::frame()

third_party/WebKit/Source/core/dom/ContextLifecycleObserver.h

Index: third_party/WebKit/Source/core/dom/ContextLifecycleObserver.h
diff --git a/third_party/WebKit/Source/core/dom/ContextLifecycleObserver.h b/third_party/WebKit/Source/core/dom/ContextLifecycleObserver.h
index fb4e51830f27e427cf49310c58ed80e5deac68b7..a2fddd3a8a0a455b98b1fea132826f8ded0d4213 100644
--- a/third_party/WebKit/Source/core/dom/ContextLifecycleObserver.h
+++ b/third_party/WebKit/Source/core/dom/ContextLifecycleObserver.h
@@ -33,11 +33,18 @@
 
 namespace blink {
 
+class LocalFrame;
+
 class CORE_EXPORT ContextLifecycleObserver
     : public LifecycleObserver<ExecutionContext, ContextLifecycleObserver> {
  public:
+  // Returns null after the observing context is detached.
   ExecutionContext* getExecutionContext() const { return lifecycleContext(); }
 
+  // Returns null after the observing context is detached or if the context
+  // doesn't have a frame (i.e., if the context is not a Document).
+  LocalFrame* frame() const;
+
   enum Type {
     GenericType,
     SuspendableObjectType,