Bug 1201907 - Enable memory tool for use and add a trait indicating its availability. r=fitzgen

devtools/client/definitions.js

@@ -285,14 +285,9 @@ Tools.memory = {
   label: "Memory",
   panelLabel: "Memory Panel",
   tooltip: "Memory (keyboardshortcut)",
-  hiddenInOptions: true,
 
   isTargetSupported: function (target) {
-    // TODO 1201907
-    // Once Fx44 lands, we should add a root trait `heapSnapshots`
-    // to indicate that the memory actor can handle this.
-    // Shouldn't make this change until Fx44, however.
-    return true; // target.getTrait("heapSnapshots");
+    return target.getTrait("heapSnapshots");
   },
 
   build: function (frame, target) {

devtools/server/actors/root.js

@@ -173,6 +173,9 @@ RootActor.prototype = {
     // Whether or not `getProfile()` supports specifying a `startTime`
     // and `endTime` to filter out samples. Fx40+
     profilerDataFilterable: true,
+    // Whether or not the MemoryActor's heap snapshot abilities are
+    // fully equipped to handle heap snapshots for the memory tool. Fx44+
+    heapSnapshots: true,
   },
 
   /**