Send web3 usage metrics once per origin/property (#9237)

The usage metrics for the injected web3 instance were being sent upon
each use, which exceeded the limits of our Matomo plan. These metrics
are now only being sent upon the first usage, for each origin and
property.

app/scripts/lib/createMethodMiddleware.js

@@ -1,3 +1,6 @@
+
+const recordedWeb3Usage = {}
+
 /**
  * Returns a middleware that implements the following RPC methods:
  * - metamask_logInjectedWeb3Usage
@@ -15,11 +18,17 @@ export default function createMethodMiddleware ({ origin, sendMetrics }) {
 
         const { action, name } = req.params[0]
 
+        if (!recordedWeb3Usage[origin]) {
+          recordedWeb3Usage[origin] = {}
+        }
+        if (!recordedWeb3Usage[origin][name]) {
+          recordedWeb3Usage[origin][name] = true
           sendMetrics({
             action,
             name,
             customVariables: { origin },
           })
+        }
 
         res.result = true
         break