Bug 1572043 - Introduce a check version method in the benchmark storage IPDL protocol.r=jya

The new protocol method transfers the database name and the version number from the content to the parent process. Then the parent process retrieves the stored version number from the database and compares it to the provided version number. If they are the same it stops there, otherwise it erases all the entries from the database and stores the new version number.

Differential Revision: https://phabricator.services.mozilla.com/D41002

--HG--
extra : moz-landing-system : lando

dom/media/mediacapabilities/BenchmarkStorageParent.cpp

@@ -100,4 +100,25 @@ IPCResult BenchmarkStorageParent::RecvGet(const nsCString& aDbName,
   return IPC_OK();
 }
 
+IPCResult BenchmarkStorageParent::RecvCheckVersion(const nsCString& aDbName,
+                                                   int32_t aVersion) {
+  mStorage->Get(aDbName, NS_LITERAL_CSTRING("Version"))
+      ->Then(
+          GetCurrentThreadSerialEventTarget(), __func__,
+          [storage = mStorage, aDbName, aVersion](int32_t aResult) {
+            if (aVersion != aResult) {
+              storage->Clear(aDbName)->Then(
+                  GetCurrentThreadSerialEventTarget(), __func__,
+                  [storage, aDbName, aVersion](bool) {
+                    storage->Put(aDbName, NS_LITERAL_CSTRING("Version"),
+                                 aVersion);
+                  },
+                  [](nsresult rv) { /*do nothing*/ });
+            }
+          },
+          [](nsresult rv) { /*do nothing*/ });
+
+  return IPC_OK();
+}
+
 };  // namespace mozilla

dom/media/mediacapabilities/BenchmarkStorageParent.h

@@ -26,6 +26,8 @@ class BenchmarkStorageParent : public PBenchmarkStorageParent {
   IPCResult RecvGet(const nsCString& aDbName, const nsCString& aKey,
                     GetResolver&& aResolve);
 
+  IPCResult RecvCheckVersion(const nsCString& aDbName, int32_t aVersion);
+
  private:
   RefPtr<KeyValueStorage> mStorage;
 };

dom/media/mediacapabilities/PBenchmarkStorage.ipdl

@@ -14,6 +14,7 @@ async protocol PBenchmarkStorage
 parent:
   async Put(nsCString aDbName, nsCString aKey, int32_t aValue);
   async Get(nsCString aDbName, nsCString aKey) returns(int32_t aValue);
+  async CheckVersion(nsCString aDbName, int32_t aVersion);
   async __delete__();
 
 };