Remove handling in inspector for Object.observe async task events

src/inspector/V8Debugger.cpp

 // Copyright 2016 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/inspector/V8Debugger.h"
 
 #include "src/inspector/DebuggerScript.h"
 #include "src/inspector/ScriptBreakpoint.h"
 #include "src/inspector/StringUtil.h"
 #include "src/inspector/V8DebuggerAgentImpl.h"
@@ skipping 632 matching lines @@
   if (!m_maxAsyncCallStackDepth) return;
 
   String16 type = toProtocolStringWithTypeCheck(
       callInternalGetterFunction(eventData, "type"));
   String16 name = toProtocolStringWithTypeCheck(
       callInternalGetterFunction(eventData, "name"));
   int id = callInternalGetterFunction(eventData, "id")
                ->ToInteger(context)
                .ToLocalChecked()
                ->Value();
-  // The scopes for the ids are defined by the eventData.name namespaces. There
-  // are currently two namespaces: "Object." and "Promise.".
-  void* ptr = reinterpret_cast<void*>(id * 4 + (name[0] == 'P' ? 2 : 0) + 1);
+  // Async task events from Promises are given misaligned pointers to prevent
+  // from overlapping with other Blink task identifiers. There is a single
+  // namespace of such ids, managed by src/js/promise.js.
+  void* ptr = reinterpret_cast<void*>(id * 2 + 1);

[adamk, 2016/09/20 22:20:03]

This used to be

id * 4 + 3

now it's

id * 2 + 1

Why should the 4 change to a 2?

[Dan Ehrenberg, 2016/09/20 22:21:58]

They were all given odd numbers. It used to alternate between Promises and
Object.observe callbacks; I just made the whole space be used by Promises
instead. This is the minimal formula to meet the non-aligned requirement. id * 4
+ 3 would be an obscure historical complication.

   if (type == v8AsyncTaskEventEnqueue)
     asyncTaskScheduled(name, ptr, false);
   else if (type == v8AsyncTaskEventWillHandle)
     asyncTaskStarted(ptr);
   else if (type == v8AsyncTaskEventDidHandle)
     asyncTaskFinished(ptr);
   else
     UNREACHABLE();
 }
 
@@ skipping 309 matching lines @@
 
   size_t stackSize =
       fullStack ? V8StackTraceImpl::maxCallStackSizeToCapture : 1;
   if (m_inspector->enabledRuntimeAgentForGroup(contextGroupId))
     stackSize = V8StackTraceImpl::maxCallStackSizeToCapture;
 
   return V8StackTraceImpl::capture(this, contextGroupId, stackSize);
 }
 
 }  // namespace v8_inspector