Add Isolate::DiscardThreadSpecificMetadata method to embedder API.

src/isolate.h

 // Copyright 2012 the V8 project 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 V8_ISOLATE_H_
 #define V8_ISOLATE_H_
 
 #include <queue>
 #include <set>
 
@@ skipping 500 matching lines @@
   void ClearSerializerData();
 
   // Find the PerThread for this particular (isolate, thread) combination
   // If one does not yet exist, return null.
   PerIsolateThreadData* FindPerThreadDataForThisThread();
 
   // Find the PerThread for given (isolate, thread) combination
   // If one does not yet exist, return null.
   PerIsolateThreadData* FindPerThreadDataForThread(ThreadId thread_id);
 
+  // Discard the PerThread for this particular (isolate, thread) combination
+  // If one does not yet exist, no-op.
+  void DiscardPerThreadDataForThisThread();
+
   // Returns the key used to store the pointer to the current isolate.
   // Used internally for V8 threads that do not execute JavaScript but still
   // are part of the domain of an isolate (like the context switcher).
   static base::Thread::LocalStorageKey isolate_key() {
     return isolate_key_;
   }
 
   // Returns the key used to store process-wide thread IDs.
   static base::Thread::LocalStorageKey thread_id_key() {
     return thread_id_key_;
@@ skipping 1020 matching lines @@
 
   EmbeddedVector<char, 128> filename_;
   FILE* file_;
   int scope_depth_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_ISOLATE_H_