DevTools: Support asynchronous call stacks on backend.

Source/devtools/protocol.json

 {
     "version": { "major": "1", "minor": "1" },
     "domains": [{
         "domain": "Inspector",
         "hidden": true,
         "types": [],
         "commands": [
             {
                 "name": "enable",
                 "description": "Enables inspector domain notifications."
@@ skipping 2947 matching lines @@
             },
             {
                 "id": "CallFrame",
                 "type": "object",
                 "properties": [
                     { "name": "callFrameId", "$ref": "CallFrameId", "description": "Call frame identifier. This identifier is only valid while the virtual machine is paused." },
                     { "name": "functionName", "type": "string", "description": "Name of the JavaScript function called on this call frame." },
                     { "name": "location", "$ref": "Location", "description": "Location in the source code." },
                     { "name": "scopeChain", "type": "array", "items": { "$ref": "Scope" }, "description": "Scope chain for this call frame." },
                     { "name": "this", "$ref": "Runtime.RemoteObject", "description": "<code>this</code> object for this call frame." },
-                    { "name": "returnValue", "$ref": "Runtime.RemoteObject", "optional": true, "hidden": true, "description": "The value being returned, if the function is at return point." }
+                    { "name": "returnValue", "$ref": "Runtime.RemoteObject", "optional": true, "hidden": true, "description": "The value being returned, if the function is at return point." },
+                    { "name": "asyncCallFrames", "type": "array", "items": { "$ref": "CallFrame" }, "optional": true, "hidden": true, "description": "Asynchronous call stack, if any." }
                 ],
                 "description": "JavaScript call frame. Array of call frames form the call stack."
             },
             {
                 "id": "Scope",
                 "type": "object",
                 "properties": [
                     { "name": "type", "type": "string", "enum": ["global", "local", "with", "closure", "catch"], "description": "Scope type." },
                     { "name": "object", "$ref": "Runtime.RemoteObject", "description": "Object representing the scope. For <code>global</code> and <code>with</code> scopes it represents the actual object; for the rest of the scopes, it is artificial transient object enumerating scope variables as its properties." }
                 ],
@@ skipping 269 matching lines @@
                 "hidden": true,
                 "description": "Returns call stack including variables changed since VM was paused. VM must be paused."
             },
             {
                 "name": "skipStackFrames",
                 "parameters": [
                     { "name": "script", "optional": true, "type": "string", "description": "Regular expression defining the scripts to ignore while stepping." }
                 ],
                 "hidden": true,
                 "description": "Makes backend skip steps in the sources with names matching given pattern. VM will try leave blacklisted scripts by performing 'step in' several times, finally resorting to 'step out' if unsuccessful."
+            },
+            {
+                "name": "setAsyncCallStackDepth",
+                "parameters": [
+                    { "name": "maxDepth", "type": "integer", "description": "Maximum depth of async call stacks. Setting to <code>0</code> will effectively disable collecting async call stacks (default)." }
+                ],
+                "hidden": true,
+                "description": "Enables or disables async call stacks tracking."
             }
         ],
         "events": [
             {
                 "name": "globalObjectCleared",
                 "description": "Called when global has been cleared and debugger client should reset its state. Happens upon navigation or reload."
             },
             {
                 "name": "scriptParsed",
                 "parameters": [
@@ skipping 776 matching lines @@
                 "parameters": [
                     { "name": "value", "type": "array", "items": { "type": "object" } }
                 ]
             },
             {
                 "name": "tracingComplete"
             }
         ]
     }]
 }