Introduce state to indicate if restoring tabs is complete

components/browser/state/src/main/java/mozilla/components/browser/state/action/BrowserAction.kt

@@ -54,6 +54,11 @@ sealed class BrowserAction : Action
  */
 object InitAction : BrowserAction()
 
+/**
+ * [BrowserAction] to indicate that restoring [BrowserState] is complete.
+ */
+object RestoreCompleteAction : BrowserAction()
+
 /**
  * [BrowserAction] implementations to react to system events.
  */

components/browser/state/src/main/java/mozilla/components/browser/state/reducer/BrowserStateReducer.kt

@@ -19,6 +19,7 @@ import mozilla.components.browser.state.action.SystemAction
 import mozilla.components.browser.state.action.TabListAction
 import mozilla.components.browser.state.action.LastAccessAction
 import mozilla.components.browser.state.action.RecentlyClosedAction
+import mozilla.components.browser.state.action.RestoreCompleteAction
 import mozilla.components.browser.state.action.TrackingProtectionAction
 import mozilla.components.browser.state.action.UndoAction
 import mozilla.components.browser.state.action.WebExtensionAction
@@ -39,6 +40,7 @@ internal object BrowserStateReducer {
     fun reduce(state: BrowserState, action: BrowserAction): BrowserState {
         return when (action) {
             is InitAction -> state
+            is RestoreCompleteAction -> state.copy(restoreComplete = true)
             is ContainerAction -> ContainerReducer.reduce(state, action)
             is RecentlyClosedAction -> RecentlyClosedReducer.reduce(state, action)
             is ContentAction -> ContentStateReducer.reduce(state, action)

components/browser/state/src/main/java/mozilla/components/browser/state/state/BrowserState.kt

@@ -23,6 +23,8 @@ import mozilla.components.lib.state.State
  * @property search the state of search for this browser state.
  * @property downloads Downloads ([DownloadState]s) mapped to their IDs.
  * @property undoHistory History of recently closed tabs to support "undo" (Requires UndoMiddleware).
+ * @property restoreComplete Whether or not restoring [BrowserState] has completed. This can be used
+ * on application startup e.g. as an indicator that tabs have been restored.
  */
 data class BrowserState(
     val tabs: List<TabSessionState> = emptyList(),
@@ -34,5 +36,6 @@ data class BrowserState(
     val media: MediaState = MediaState(),
     val downloads: Map<String, DownloadState> = emptyMap(),
     val search: SearchState = SearchState(),
-    val undoHistory: UndoHistoryState = UndoHistoryState()
+    val undoHistory: UndoHistoryState = UndoHistoryState(),
+    val restoreComplete: Boolean = false
 ) : State

components/browser/state/src/test/java/mozilla/components/browser/state/store/BrowserStoreTest.kt

@@ -7,12 +7,15 @@ package mozilla.components.browser.state.store
 import kotlinx.coroutines.runBlocking
 import mozilla.components.browser.state.action.BrowserAction
 import mozilla.components.browser.state.action.InitAction
+import mozilla.components.browser.state.action.RestoreCompleteAction
 import mozilla.components.browser.state.action.TabListAction
 import mozilla.components.browser.state.state.BrowserState
 import mozilla.components.browser.state.state.createTab
 import mozilla.components.lib.state.Middleware
+import mozilla.components.support.test.ext.joinBlocking
 import mozilla.components.support.test.libstate.ext.waitUntilIdle
 import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
 import org.junit.Assert.assertNull
 import org.junit.Assert.assertTrue
 import org.junit.Test
@@ -77,4 +80,16 @@ class BrowserStoreTest {
         store.waitUntilIdle()
         assertTrue(initActionObserved)
     }
+
+    @Test
+    fun `RestoreCompleteAction updates state`() {
+        val store = BrowserStore()
+        assertFalse(store.state.restoreComplete)
+
+        store.dispatch(RestoreCompleteAction).joinBlocking()
+        assertTrue(store.state.restoreComplete)
+
+        store.dispatch(RestoreCompleteAction).joinBlocking()
+        assertTrue(store.state.restoreComplete)
+    }
 }