For #10342 - Part 1: Remove top sites prefetch and observation of live data

app/src/main/java/org/mozilla/fenix/FenixApplication.kt

@@ -141,7 +141,6 @@ open class FenixApplication : LocaleAwareApplication(), Provider {
             }
         }
 
-        prefetchForHomeFragment()
         setupLeakCanary()
         startMetricsIfEnabled()
         setupPush()
@@ -257,14 +256,6 @@ open class FenixApplication : LocaleAwareApplication(), Provider {
         // no-op, LeakCanary is disabled by default
     }
 
-    // This is for issue https://github.com/mozilla-mobile/fenix/issues/11660. We prefetch our info for startup
-    // so that we're sure that we have all the data available as our fragment is launched.
-    private fun prefetchForHomeFragment() {
-        StrictMode.allowThreadDiskReads().resetPoliciesAfter {
-            components.core.topSiteStorage.prefetch()
-        }
-    }
-
     private fun setupPush() {
         // Sets the PushFeature as the singleton instance for push messages to go to.
         // We need the push feature setup here to deliver messages in the case where the service

app/src/main/java/org/mozilla/fenix/ext/LiveData.kt

@@ -1,20 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-package org.mozilla.fenix.ext
-
-import androidx.lifecycle.LiveData
-import androidx.lifecycle.Observer
-
-/**
- * Observe a LiveData once and unregister from it as soon as the live data returns a value
- */
-fun <T> LiveData<T>.observeOnce(observer: (T) -> Unit) {
-    observeForever(object : Observer<T> {
-        override fun onChanged(value: T) {
-            removeObserver(this)
-            observer(value)
-        }
-    })
-}

app/src/main/java/org/mozilla/fenix/home/HomeFragment.kt

@@ -68,7 +68,6 @@ import mozilla.components.concept.sync.AccountObserver
 import mozilla.components.concept.sync.AuthType
 import mozilla.components.concept.sync.OAuthAccount
 import mozilla.components.feature.tab.collections.TabCollection
-import mozilla.components.feature.top.sites.TopSite
 import mozilla.components.lib.state.ext.consumeFrom
 import mozilla.components.support.ktx.android.util.dpToPx
 import org.mozilla.fenix.BrowserDirection
@@ -511,7 +510,6 @@ class HomeFragment : Fragment() {
     override fun onStart() {
         super.onStart()
         subscribeToTabCollections()
-        subscribeToTopSites()
 
         val context = requireContext()
         val components = context.components
@@ -847,17 +845,6 @@ class HomeFragment : Fragment() {
         }
     }
 
-    private fun subscribeToTopSites(): Observer<List<TopSite>> {
-        return Observer<List<TopSite>> { topSites ->
-            requireComponents.core.topSiteStorage.cachedTopSites = topSites
-            context?.settings()?.preferences?.edit()
-                ?.putInt(getString(R.string.pref_key_top_sites_size), topSites.size)?.apply()
-            homeFragmentStore.dispatch(HomeFragmentAction.TopSitesChange(topSites))
-        }.also { observer ->
-            requireComponents.core.topSiteStorage.getTopSites().observe(this, observer)
-        }
-    }
-
     private fun registerCollectionStorageObserver() {
         requireComponents.core.tabCollectionStorage.register(collectionStorageObserver, this)
     }