Add the rate of js invocations from the api as a signal of idleness

src/isolate.cc

 // 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.
 
 #include "src/isolate.h"
 
 #include <stdlib.h>
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
@@ skipping 1774 matching lines @@
       initialized_from_snapshot_(false),
       cpu_profiler_(NULL),
       heap_profiler_(NULL),
       function_entry_hook_(NULL),
       deferred_handles_head_(NULL),
       optimizing_compile_dispatcher_(NULL),
       stress_deopt_count_(0),
       virtual_handler_register_(NULL),
       virtual_slot_register_(NULL),
       next_optimization_id_(0),
+      js_calls_from_api_counter_(0),
 #if TRACE_MAPS
       next_unique_sfi_id_(0),
 #endif
       use_counter_callback_(NULL),
       basic_block_profiler_(NULL),
       abort_on_uncaught_exception_callback_(NULL) {
   {
     base::LockGuard<base::Mutex> lock_guard(thread_data_table_mutex_.Pointer());
     CHECK(thread_data_table_);
   }
@@ skipping 1045 matching lines @@
   // Then check whether this scope intercepts.
   if ((flag & intercept_mask_)) {
     intercepted_flags_ |= flag;
     return true;
   }
   return false;
 }
 
 }  // namespace internal
 }  // namespace v8