Moved isolate high watermark calculations into the Observatory client.

runtime/vm/isolate.cc

Index: runtime/vm/isolate.cc
diff --git a/runtime/vm/isolate.cc b/runtime/vm/isolate.cc
index b5a139be71e7a012a677d2f00039b1d4fe91fbe6..120b1d353b1a395d2187af6262db7c25bef58f9d 100644
--- a/runtime/vm/isolate.cc
+++ b/runtime/vm/isolate.cc
@@ -783,7 +783,6 @@ Isolate::Isolate(const Dart_IsolateFlags& api_flags)
       single_step_(false),
       thread_registry_(new ThreadRegistry()),
       safepoint_handler_(new SafepointHandler(this)),
-      memory_high_watermark_(0),
       message_notify_callback_(NULL),
       name_(NULL),
       debugger_name_(NULL),
@@ -2118,7 +2117,6 @@ void Isolate::PrintJSON(JSONStream* stream, bool ref) {
     }
   }
 
-  jsobj.AddPropertyF("_memoryHighWatermark", "%" Pu "", memory_high_watermark_);
   jsobj.AddProperty("_threads", thread_registry_);
 }
 #endif
@@ -2717,7 +2715,6 @@ void Isolate::UnscheduleThread(Thread* thread,
     // Ensure that the thread reports itself as being at a safepoint.
     thread->EnterSafepoint();
   }
-  UpdateMemoryHighWatermark();
   OSThread* os_thread = thread->os_thread();
   ASSERT(os_thread != NULL);
   os_thread->DisableThreadInterrupts();
@@ -2738,15 +2735,6 @@ void Isolate::UnscheduleThread(Thread* thread,
 }
 
 
-void Isolate::UpdateMemoryHighWatermark() {
-  const uintptr_t thread_watermarks_total =
-      thread_registry()->ThreadHighWatermarksTotalLocked();
-  if (thread_watermarks_total > memory_high_watermark_) {
-    memory_high_watermark_ = thread_watermarks_total;
-  }
-}
-
-
 static RawInstance* DeserializeObject(Thread* thread,
                                       uint8_t* obj_data,
                                       intptr_t obj_len) {