GC plugin: remove mixin trace override restriction.

tools/clang/blink_gc_plugin/RecordInfo.h

 // Copyright 2014 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.
 
 // This file provides a wrapper for CXXRecordDecl that accumulates GC related
 // information about a class. Accumulated information is memoized and the info
 // objects are stored in a RecordCache.
 
 #ifndef TOOLS_BLINK_GC_PLUGIN_RECORD_INFO_H_
 #define TOOLS_BLINK_GC_PLUGIN_RECORD_INFO_H_
@@ skipping 75 matching lines @@
   bool GetTemplateArgs(size_t count, TemplateArgs* output_args);
 
   bool IsHeapAllocatedCollection();
   bool IsGCDerived();
   bool IsGCAllocated();
   bool IsGCFinalized();
   bool IsGCMixin();
   bool IsStackAllocated();
   bool IsNonNewable();
   bool IsOnlyPlacementNewable();
-  bool IsGCMixinInstance();
   bool IsEagerlyFinalized();
   bool IsGCRefCounted();
 
   bool HasDefinition();
 
   clang::CXXMethodDecl* DeclaresNewOperator();
 
   bool RequiresTraceMethod();
   bool NeedsFinalization();
   bool DeclaresGCMixinMethods();
@@ skipping 75 matching lines @@
       }
     }
   }
 
  private:
   typedef std::map<clang::CXXRecordDecl*, RecordInfo> Cache;
   Cache cache_;
 };
 
 #endif  // TOOLS_BLINK_GC_PLUGIN_RECORD_INFO_H_