Issue mozilla-mobile#35: Integrate "engine" component.

app/build.gradle

@@ -68,6 +68,15 @@ repositories {
 dependencies {
     implementation "io.sentry:sentry-android:${rootProject.ext.dependencies['sentry']}"
 
+    implementation "org.mozilla.components:engine:${rootProject.ext.dependencies['mozillaComponents']}"
+    implementation "org.mozilla.components:engine-gecko:${rootProject.ext.dependencies['mozillaComponents']}"
+    implementation "org.mozilla.components:session:${rootProject.ext.dependencies['mozillaComponents']}"
+    implementation "org.mozilla.components:abstract-toolbar:${rootProject.ext.dependencies['mozillaComponents']}"
+    implementation "org.mozilla.components:toolbar:${rootProject.ext.dependencies['mozillaComponents']}"
+    implementation "org.mozilla.components:feature-session:${rootProject.ext.dependencies['mozillaComponents']}"
+    implementation "org.mozilla.components:feature-toolbar:${rootProject.ext.dependencies['mozillaComponents']}"
+    implementation "org.mozilla.components:ktx:${rootProject.ext.dependencies['mozillaComponents']}"
+
     armImplementation "org.mozilla:geckoview-nightly-armeabi-v7a:${rootProject.ext.gecko['version']}"
     x86Implementation "org.mozilla:geckoview-nightly-x86:${rootProject.ext.gecko['version']}"
     aarch64Implementation "org.mozilla:geckoview-nightly-arm64-v8a:${rootProject.ext.gecko['version']}"

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

@@ -7,8 +7,11 @@ package mozilla.fenix
 import android.app.Application
 import io.sentry.Sentry
 import io.sentry.android.AndroidSentryClientFactory
+import mozilla.fenix.components.Components
 
 class FenixApplication : Application() {
+    val components by lazy { Components(this) }
+
     override fun onCreate() {
         super.onCreate()
 

app/src/main/java/mozilla/fenix/MainActivity.kt

@@ -4,13 +4,34 @@
 
 package mozilla.fenix
 
+import android.content.Context
 import android.os.Bundle
 import android.support.v7.app.AppCompatActivity
+import android.util.AttributeSet
+import android.view.View
+import kotlinx.android.synthetic.main.activity_main.*
+import mozilla.components.concept.engine.EngineView
+import mozilla.components.feature.session.SessionFeature
+import mozilla.fenix.components.FeatureLifecycleObserver
+import mozilla.fenix.ext.components
 
 class MainActivity : AppCompatActivity() {
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
+
+        val sessionFeature = SessionFeature(components.sessionManager, components.sessionUseCases,
+                components.engine, engineView, components.sessionMapping)
+
+        lifecycle.addObserver(FeatureLifecycleObserver(sessionFeature))
+    }
+
+    override fun onCreateView(parent: View?, name: String?, context: Context?, attrs: AttributeSet?): View? {
+        if (name == EngineView::class.java.name) {
+            return components.engine.createView(context!!, attrs).asView()
+        }
+
+        return super.onCreateView(parent, name, context, attrs)
     }
 }

app/src/main/java/mozilla/fenix/components/Components.kt

@@ -0,0 +1,33 @@
+/* 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 mozilla.fenix.components
+
+import android.content.Context
+import mozilla.components.browser.engine.gecko.GeckoEngine
+import mozilla.components.browser.session.SessionManager
+import mozilla.components.browser.session.SessionProvider
+import mozilla.components.concept.engine.Engine
+import mozilla.components.feature.session.SessionMapping
+import mozilla.components.feature.session.SessionUseCases
+import mozilla.fenix.components.session.DefaultSessionProvider
+import org.mozilla.geckoview.GeckoRuntime
+import org.mozilla.geckoview.GeckoRuntimeSettings
+
+/**
+ * Helper class for lazily instantiating components needed by the application.
+ */
+class Components(private val applicationContext: Context) {
+    private val geckoRuntime by lazy {
+        val settings = GeckoRuntimeSettings()
+        GeckoRuntime.create(applicationContext, settings)
+    }
+
+    val engine : Engine by lazy { GeckoEngine(geckoRuntime) }
+
+    private val sessionProvider: SessionProvider by lazy { DefaultSessionProvider() }
+    val sessionManager by lazy { SessionManager(sessionProvider) }
+    val sessionMapping by lazy { SessionMapping() }
+    val sessionUseCases by lazy { SessionUseCases(sessionManager, engine, sessionMapping) }
+}

app/src/main/java/mozilla/fenix/components/FeatureLifecycleObserver.kt

@@ -0,0 +1,27 @@
+/* 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 mozilla.fenix.components
+
+import android.arch.lifecycle.Lifecycle
+import android.arch.lifecycle.LifecycleObserver
+import android.arch.lifecycle.OnLifecycleEvent
+import mozilla.components.feature.session.SessionFeature
+
+/**
+ * LifecycleObserver implementation that will forward lifecycle callbacks to "feature" components.
+ */
+class FeatureLifecycleObserver(
+    private val sessionFeature: SessionFeature
+): LifecycleObserver {
+    @OnLifecycleEvent(Lifecycle.Event.ON_START)
+    fun startFeatures() {
+        sessionFeature.start()
+    }
+
+    @OnLifecycleEvent(Lifecycle.Event.ON_STOP)
+    fun stopFeatures() {
+        sessionFeature.stop()
+    }
+}

app/src/main/java/mozilla/fenix/components/session/DefaultSessionProvider.kt

@@ -0,0 +1,16 @@
+/* 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 mozilla.fenix.components.session
+
+import mozilla.components.browser.session.Session
+import mozilla.components.browser.session.SessionProvider
+
+class DefaultSessionProvider: SessionProvider {
+    override fun getInitialSessions(): Pair<List<Session>, Int> {
+        // For now we start with a very simple session provider that will always start with a session
+        // that contains mozilla.org.
+        return Pair(listOf(Session("https://www.mozilla.org")), 0)
+    }
+}

app/src/main/java/mozilla/fenix/ext/Context.kt

@@ -0,0 +1,21 @@
+/* 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 mozilla.fenix.ext
+
+import android.content.Context
+import mozilla.fenix.components.Components
+import mozilla.fenix.FenixApplication
+
+/**
+ * Get the FenixApplication object from a context.
+ */
+val Context.application: FenixApplication
+    get() = applicationContext as FenixApplication
+
+/**
+ * Get the components of this application.
+ */
+val Context.components: Components
+    get() = application.components

app/src/main/res/layout/activity_main.xml

@@ -2,24 +2,17 @@
 <!-- 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/. -->
-<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
+    android:orientation="vertical"
     tools:context=".MainActivity">
 
-    <ImageView
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:layout_marginBottom="8dp"
-        android:layout_marginEnd="8dp"
-        android:layout_marginStart="8dp"
-        android:layout_marginTop="8dp"
-        android:src="@mipmap/ic_launcher"
-        app:layout_constraintBottom_toBottomOf="parent"
-        app:layout_constraintEnd_toEndOf="parent"
-        app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toTopOf="parent" />
+    <mozilla.components.concept.engine.EngineView
+        android:id="@+id/engineView"
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        android:layout_weight="1" />
 
-</android.support.constraint.ConstraintLayout>
+</LinearLayout>

build.gradle

@@ -7,9 +7,11 @@ buildscript {
         kotlin: '1.2.40',
         sentry: '1.7.3',
         supportLibraries: '27.1.1',
-        junit: '4.12',
         constraintLayout: '1.1.0',
-        mozillaComponents: '0.5'
+        // Testing
+        junit: '4.12',
+        // Mozilla
+        mozillaComponents: '0.5.1'
     ]
 
     ext.gecko = [