[heap] Reland "Use RAIL mode for initial heap sizing"

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 <memory>
 #include <queue>
 
@@ skipping 1159 matching lines @@
   // Clear all optimized code stored in native contexts.
   void ClearOSROptimizedCode();
 
   // Ensure that a particular optimized code is evicted.
   void EvictOSROptimizedCode(Code* code, const char* reason);
 
   bool IsInAnyContext(Object* object, uint32_t index);
 
   void SetRAILMode(RAILMode rail_mode);
 
+  RAILMode rail_mode() { return rail_mode_.Value(); }
+
+  double LoadStartTimeMs();
+
   void IsolateInForegroundNotification();
 
   void IsolateInBackgroundNotification();
 
   bool IsIsolateInBackground() { return is_isolate_in_background_; }
 
   PRINTF_FORMAT(2, 3) void PrintWithTimestamp(const char* format, ...);
 
 #ifdef USE_SIMULATOR
   base::Mutex* simulator_i_cache_mutex() { return &simulator_i_cache_mutex_; }
@@ skipping 165 matching lines @@
   unibrow::Mapping<unibrow::CanonicalizationRange> jsregexp_canonrange_;
   unibrow::Mapping<unibrow::Ecma262Canonicalize>
       regexp_macro_assembler_canonicalize_;
   RegExpStack* regexp_stack_;
   List<int> regexp_indices_;
   DateCache* date_cache_;
   CallInterfaceDescriptorData* call_descriptor_data_;
   AccessCompilerData* access_compiler_data_;
   base::RandomNumberGenerator* random_number_generator_;
   base::AtomicValue<RAILMode> rail_mode_;
+  base::Mutex rail_mutex_;
+  double load_start_time_ms_;
 
   // Whether the isolate has been created for snapshotting.
   bool serializer_enabled_;
 
   // True if fatal error has been signaled for this isolate.
   bool has_fatal_error_;
 
   // True if this isolate was initialized from a snapshot.
   bool initialized_from_snapshot_;
 
@@ skipping 318 matching lines @@
 
   EmbeddedVector<char, 128> filename_;
   FILE* file_;
   int scope_depth_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_ISOLATE_H_