Add a DevTools command to create an isolated world for a given frame

third_party/WebKit/Source/bindings/core/v8/ScriptController.cpp

Index: third_party/WebKit/Source/bindings/core/v8/ScriptController.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/ScriptController.cpp b/third_party/WebKit/Source/bindings/core/v8/ScriptController.cpp
index 8f03da4fe08d79e3a69f87743a86a5ce465c4aad..a3b05cb65202906b239b01a79cc2075f763fbd3b 100644
--- a/third_party/WebKit/Source/bindings/core/v8/ScriptController.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/ScriptController.cpp
@@ -60,6 +60,7 @@
 #include "platform/instrumentation/tracing/TraceEvent.h"
 #include "platform/weborigin/SecurityOrigin.h"
 #include "platform/wtf/CurrentTime.h"
+#include "platform/wtf/HashSet.h"
 #include "platform/wtf/StdLibExtras.h"
 #include "platform/wtf/StringExtras.h"
 #include "platform/wtf/text/CString.h"
@@ -371,4 +372,29 @@ void ScriptController::ExecuteScriptInIsolatedWorld(
   }
 }
 
+int ScriptController::CreateNewIsolatedWorld(const String& world_name) {
+  // Find an unused id, unfortunately there doesn't seem to be a better way of
+  // doing this because DOMWrapperWorld::Create doesn't support isolated worlds.
+  Vector<RefPtr<DOMWrapperWorld>> worlds;
+  DOMWrapperWorld::AllWorldsInCurrentThread(worlds);
+  WTF::HashSet<int> existingWorlds;
+  for (const auto& world : worlds) {
+    if (!world->IsIsolatedWorld())
+      continue;
+    existingWorlds.insert(world->GetWorldId());
+  }
+  int world_id = 1;

[caseq, 2017/04/28 21:41:30]

I think allocating ids like this is going to bring some unpleasant surprises due
to collisions with other world id users that presume authority over their id
range and would not check if the world already exists. 

[Sami, 2017/05/02 09:47:19]

Is there some registry of world ids? Should we just start at a higher number to
make collisions less likely? In any case, I would prefer to have the
implementation allocate ids instead of assuming users (e.g., different
libraries) can keep their ids straight.

[alex clarke (OOO till 29th), 2017/05/02 10:00:06]

OK do you have any suggestions for what else we might do?

+  while (existingWorlds.Contains(world_id)) {
+    world_id++;
+  }
+  DCHECK_LT(world_id, DOMWrapperWorld::kEmbedderWorldIdLimit);
+  RefPtr<DOMWrapperWorld> world =
+      DOMWrapperWorld::EnsureIsolatedWorld(GetIsolate(), world_id);
+
+  DOMWrapperWorld::SetIsolatedWorldHumanReadableName(world_id, world_name);
+  // Make sure the execution context exists.
+  WindowProxy(*world);
+  return world_id;
+}
+
 }  // namespace blink