Add better documentation for the call tree strategies

src/actions/profile-view.js

@@ -940,6 +940,11 @@ export function changeImplementationFilter(
   };
 }
 
+/**
+ * This action changes the strategy used to build and display the call tree. This could
+ * use sample data, or build a new call tree based off of allocation information stored
+ * in markers.
+ */
 export function changeCallTreeSummaryStrategy(
   strategy: CallTreeSummaryStrategy
 ): Action {

src/profile-logic/profile-data.js

@@ -697,8 +697,11 @@ export function toValidCallTreeSummaryStrategy(
     case 'native-allocations':
       return strategy;
     default:
-      // Default to timing if the strategy is not recognized. This value can come
+      // Default to "timing" if the strategy is not recognized. This value can come
       // from a user-generated URL.
+      // e.g. `profiler.firefox.com/public/hash/ctSummary=tiiming` (note the typo.)
+      // This default branch will ensure we don't send values we don't understand to
+      // the store.
       return 'timing';
   }
 }