Issue #929: Use browser-session component for browser state.

app/build.gradle

@@ -147,8 +147,6 @@ dependencies {
     implementation "com.android.support:leanback-v17:$support_libraries_version"
     implementation "com.android.support.constraint:constraint-layout:$constrained_layout_version"
 
-    implementation "android.arch.lifecycle:extensions:$architecture_components_version"
-
     implementation 'com.squareup.okhttp3:okhttp:3.10.0'
     implementation 'com.squareup.picasso:picasso:2.71828', {
         // We temporarily don't include the packaged the support libs to avoid version mismatch.
@@ -165,6 +163,8 @@ dependencies {
         transitive = false
     }
 
+    implementation "org.mozilla.components:session:$moz_components_version"
+    implementation "org.mozilla.components:engine:$moz_components_version"
     implementation "org.mozilla.components:telemetry:$moz_components_version"
     implementation "org.mozilla.photon:colors:$moz_components_version"
     implementation "org.mozilla.photon:fonts:$moz_components_version"

app/src/amazonWebview/java/org/mozilla/focus/webview/FirefoxAmazonWebView.kt

@@ -15,10 +15,11 @@ import android.util.AttributeSet
 import android.view.View
 import com.amazon.android.webkit.AmazonWebChromeClient
 import com.amazon.android.webkit.AmazonWebView
+import mozilla.components.browser.session.Session
 import org.mozilla.focus.ext.deleteData
+import org.mozilla.focus.ext.savedWebViewState
 import org.mozilla.focus.iwebview.FirefoxAmazonFocusedDOMElementCache
 import org.mozilla.focus.iwebview.IWebView
-import org.mozilla.focus.session.Session
 import org.mozilla.focus.utils.UrlUtils
 
 private val uiHandler = Handler(Looper.getMainLooper())
@@ -101,10 +102,10 @@ internal class FirefoxAmazonWebView(
     }
 
     override fun restoreWebViewState(session: Session) {
-        val stateData = session.webViewState
+        val stateData = session.savedWebViewState
 
         val backForwardList = if (stateData != null) super.restoreState(stateData) else null
-        val desiredURL = session.url.value
+        val desiredURL = session.url
 
         client.restoreState(stateData)
         client.notifyCurrentURL(desiredURL)
@@ -135,7 +136,7 @@ internal class FirefoxAmazonWebView(
         super.saveState(stateData)
         client.saveState(this, stateData)
 
-        session.saveWebViewState(stateData)
+        session.savedWebViewState = stateData
     }
 
     override fun setBlockingEnabled(enabled: Boolean) {

app/src/gecko/java/org/mozilla/focus/iwebview/WebViewProvider.java

@@ -14,11 +14,11 @@
 
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
-import org.mozilla.focus.session.Session;
 import org.mozilla.gecko.GeckoView;
 import org.mozilla.gecko.GeckoViewSettings;
 
 import kotlin.NotImplementedError;
+import mozilla.components.browser.session.Session;
 
 /**
  * WebViewProvider implementation for creating a Gecko based implementation of IWebView.
@@ -234,6 +234,7 @@ public void removeJavascriptInterface(@Nullable String interfaceName) {
 
         }
 
+
         @Override
         public void restoreWebViewState(Session session) {
             // TODO: restore navigation history, and reopen previously opened page

app/src/main/java/org/mozilla/focus/Components.kt

@@ -0,0 +1,38 @@
+/* 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.focus
+
+import android.content.Context
+import android.util.AttributeSet
+import mozilla.components.browser.session.SessionManager
+import mozilla.components.concept.engine.Engine
+import mozilla.components.concept.engine.EngineSession
+import mozilla.components.concept.engine.EngineView
+
+/**
+ * Helper class for lazily instantiating and keeping references to components needed by the
+ * application.
+ */
+class Components {
+    val sessionManager by lazy { SessionManager(DummyEngine()) }
+}
+
+/**
+ * We are not using an "Engine" implementation yet. Therefore we create this dummy that we pass to
+ * the <code>SessionManager</code> for now.
+ */
+private class DummyEngine : Engine {
+    override fun createSession(): EngineSession {
+        throw NotImplementedError()
+    }
+
+    override fun createView(context: Context, attrs: AttributeSet?): EngineView {
+        throw NotImplementedError()
+    }
+
+    override fun name(): String {
+        throw NotImplementedError()
+    }
+}

app/src/main/java/org/mozilla/focus/FocusApplication.kt

@@ -18,6 +18,16 @@ class FocusApplication : LocaleAwareApplication() {
     lateinit var visibilityLifeCycleCallback: VisibilityLifeCycleCallback
         private set
 
+    /**
+     * Reference to components needed by the application.
+     *
+     * We create this instance lazily because at the time FocusApplication gets constructed it is
+     * not a valid Context object just yet (The Android system needs to call attachBaseContext()
+     * first). Therefore we delay the creation so that the components can access and use the
+     * application context at the time they get created.
+     */
+    val components by lazy { Components() }
+
     override fun onCreate() {
         super.onCreate()
 

app/src/main/java/org/mozilla/focus/MainActivity.kt

@@ -14,18 +14,18 @@ import android.view.View
 import com.amazon.android.webkit.AmazonWebKitFactories
 import com.amazon.android.webkit.AmazonWebKitFactory
 import kotlinx.android.synthetic.main.activity_main.*
-import org.mozilla.focus.architecture.NonNullObserver
+import mozilla.components.browser.session.Session
+import mozilla.components.browser.session.SessionManager
 import org.mozilla.focus.browser.BrowserFragment
 import org.mozilla.focus.browser.BrowserFragment.Companion.APP_URL_HOME
 import org.mozilla.focus.browser.VideoVoiceCommandMediaSession
+import org.mozilla.focus.ext.components
 import org.mozilla.focus.ext.toSafeIntent
 import org.mozilla.focus.home.pocket.Pocket
 import org.mozilla.focus.home.pocket.PocketOnboardingActivity
 import org.mozilla.focus.iwebview.IWebView
 import org.mozilla.focus.iwebview.WebViewProvider
 import org.mozilla.focus.locale.LocaleAwareAppCompatActivity
-import org.mozilla.focus.session.Session
-import org.mozilla.focus.session.SessionManager
 import org.mozilla.focus.session.Source
 import org.mozilla.focus.telemetry.SentryWrapper
 import org.mozilla.focus.telemetry.TelemetryWrapper
@@ -43,12 +43,31 @@ interface MediaSessionHolder {
 
 class MainActivity : LocaleAwareAppCompatActivity(), OnUrlEnteredListener, MediaSessionHolder {
 
-    private val sessionManager = SessionManager.getInstance()
-
     // There should be at most one MediaSession per process, hence it's in MainActivity.
     // We crash if we init MediaSession at init time, hence lateinit.
     override lateinit var videoVoiceCommandMediaSession: VideoVoiceCommandMediaSession
 
+    private val sessionObserver = object : SessionManager.Observer {
+        override fun onSessionSelected(session: Session) {
+            ScreenController.showBrowserScreenForCurrentSession(supportFragmentManager, session)
+        }
+
+        override fun onSessionRemoved(session: Session) {
+            if (components.sessionManager.sessions.isEmpty()) {
+                onNoActiveSession()
+            }
+        }
+
+        override fun onAllSessionsRemoved() {
+            onNoActiveSession()
+        }
+
+        private fun onNoActiveSession() {
+            // There's no active session. Start a new session with "homepage".
+            ScreenController.showBrowserScreenForUrl(this@MainActivity, supportFragmentManager, APP_URL_HOME, Source.NONE)
+        }
+    }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 
@@ -66,17 +85,14 @@ class MainActivity : LocaleAwareAppCompatActivity(), OnUrlEnteredListener, Media
         setContentView(R.layout.activity_main)
 
         IntentValidator.validateOnCreate(this, intent, savedInstanceState, ::onValidBrowserIntent)
-        sessionManager.sessions.observe(this, object : NonNullObserver<List<Session>>() {
-            public override fun onValueChanged(value: List<Session>) {
-                val sessions = value
-                if (sessions.isEmpty()) {
-                    // There's no active session. Start a new session with "homepage".
-                    ScreenController.showBrowserScreenForUrl(supportFragmentManager, APP_URL_HOME, Source.NONE)
-                } else {
-                    ScreenController.showBrowserScreenForCurrentSession(supportFragmentManager, sessionManager)
-                }
-            }
-        })
+
+        components.sessionManager.register(sessionObserver, owner = this)
+
+        if (components.sessionManager.sessions.isEmpty()) {
+            ScreenController.showBrowserScreenForUrl(this@MainActivity, supportFragmentManager, APP_URL_HOME, Source.NONE)
+        } else {
+            ScreenController.showBrowserScreenForCurrentSession(supportFragmentManager, components.sessionManager.selectedSession)
+        }
 
         if (Settings.getInstance(this@MainActivity).shouldShowPocketOnboarding()) {
             val onboardingIntents =
@@ -97,7 +113,7 @@ class MainActivity : LocaleAwareAppCompatActivity(), OnUrlEnteredListener, Media
     }
 
     private fun onValidBrowserIntent(url: String, source: Source) {
-        ScreenController.showBrowserScreenForUrl(supportFragmentManager, url, source)
+        ScreenController.showBrowserScreenForUrl(this, supportFragmentManager, url, source)
     }
 
     override fun applyLocale() {

app/src/main/java/org/mozilla/focus/ScreenController.kt

@@ -8,10 +8,12 @@ package org.mozilla.focus
 import android.content.Context
 import android.support.v4.app.FragmentManager
 import android.text.TextUtils
+import mozilla.components.browser.session.Session
 import org.mozilla.focus.browser.BrowserFragment
+import org.mozilla.focus.ext.components
+import org.mozilla.focus.ext.source
 import org.mozilla.focus.home.pocket.Pocket
 import org.mozilla.focus.home.pocket.PocketVideoFragment
-import org.mozilla.focus.session.SessionManager
 import org.mozilla.focus.session.Source
 import org.mozilla.focus.telemetry.TelemetryWrapper
 import org.mozilla.focus.telemetry.UrlTextInputLocation
@@ -33,7 +35,7 @@ object ScreenController {
         val isUrl = UrlUtils.isUrl(urlStr)
         val updatedUrlStr = if (isUrl) UrlUtils.normalize(urlStr) else UrlUtils.createSearchUrl(context, urlStr)
 
-        showBrowserScreenForUrl(fragmentManager, updatedUrlStr, Source.USER_ENTERED)
+        showBrowserScreenForUrl(context, fragmentManager, updatedUrlStr, Source.USER_ENTERED)
 
         if (isTextInput) {
             // Non-text input events are handled at the source, e.g. home tile click events.
@@ -56,11 +58,9 @@ object ScreenController {
                 .commit()
     }
 
-    fun showBrowserScreenForCurrentSession(fragmentManager: FragmentManager, sessionManager: SessionManager) {
-        val currentSession = sessionManager.currentSession
-
+    fun showBrowserScreenForCurrentSession(fragmentManager: FragmentManager, session: Session) {
         val fragment = fragmentManager.findFragmentByTag(BrowserFragment.FRAGMENT_TAG) as BrowserFragment?
-        if (fragment != null && fragment.session.isSameAs(currentSession)) {
+        if (fragment != null && fragment.session == session) {
             // There's already a BrowserFragment displaying this session.
             return
         }
@@ -69,11 +69,11 @@ object ScreenController {
         fragmentManager
                 .beginTransaction()
                 .replace(R.id.container,
-                        BrowserFragment.createForSession(currentSession), BrowserFragment.FRAGMENT_TAG)
+                        BrowserFragment.createForSession(session), BrowserFragment.FRAGMENT_TAG)
                 .commit()
     }
 
-    fun showBrowserScreenForUrl(fragmentManager: FragmentManager, url: String, source: Source) {
+    fun showBrowserScreenForUrl(context: Context, fragmentManager: FragmentManager, url: String, source: Source) {
         // This code is not correct:
         // - We only support one session but it creates a new session when there's no BrowserFragment
         // such as each time we open a URL from the home screen.
@@ -89,7 +89,10 @@ object ScreenController {
             // for visibility in addition to existence.
             browserFragment.loadUrl(url)
         } else {
-            SessionManager.getInstance().createSession(source, url)
+            val session = Session(url).apply {
+                this.source = source
+            }
+            context.components.sessionManager.add(session)
         }
     }
 

app/src/main/java/org/mozilla/focus/SettingsFragment.kt

@@ -13,9 +13,9 @@ import android.view.ViewGroup
 import android.view.accessibility.AccessibilityManager
 import kotlinx.android.synthetic.main.fragment_settings.*
 import org.mozilla.focus.browser.InfoActivity
+import org.mozilla.focus.ext.components
 import org.mozilla.focus.ext.getAccessibilityManager
 import org.mozilla.focus.ext.isVoiceViewEnabled
-import org.mozilla.focus.session.SessionManager
 import org.mozilla.focus.telemetry.DataUploadPreference
 import org.mozilla.focus.telemetry.TelemetryWrapper
 
@@ -46,13 +46,13 @@ class SettingsFragment : Fragment() {
             builder1.setCancelable(true)
 
             builder1.setPositiveButton(
-                    getString(R.string.action_ok),
-                    { dialog, _ ->
-                        settingsWebView.cleanup()
-                        SessionManager.getInstance().removeAllSessions()
-                        dialog.cancel()
-                        TelemetryWrapper.clearDataEvent()
-                    })
+                getString(R.string.action_ok)
+            ) { dialog, _ ->
+                settingsWebView.cleanup()
+                context!!.components.sessionManager.removeAll()
+                dialog.cancel()
+                TelemetryWrapper.clearDataEvent()
+            }
 
             builder1.setNegativeButton(
                     getString(R.string.action_cancel),