Bug 1061969 - Ensure the memory is not flushed when the priority is updated. r=gsvelto

dom/ipc/ProcessPriorityManager.cpp

@@ -1105,10 +1105,6 @@ ParticularProcessPriorityManager::SetPriorityNow(ProcessPriority aPriority,
     unused << mContentParent->SendNotifyProcessPriorityChanged(mPriority);
   }
 
-  if (aPriority < PROCESS_PRIORITY_FOREGROUND) {
-    unused << mContentParent->SendFlushMemory(NS_LITERAL_STRING("low-memory"));
-  }
-
   FireTestOnlyObserverNotification("process-priority-set",
     ProcessPriorityToString(mPriority, mCPUPriority));
 

dom/ipc/TabChild.cpp

@@ -2861,6 +2861,12 @@ TabChild::MakeHidden()
     if (mWidget) {
         mWidget->Show(false);
     }
+
+    nsCOMPtr<nsIObserverService> os =
+        mozilla::services::GetObserverService();
+    if (os) {
+        os->NotifyObservers(nullptr, "memory-pressure", NS_LITERAL_STRING("heap-minimize").get());
+    }
 }
 
 void