Reland "Updated background execution implementation for Android" (#5954)

* Reland "Updated background execution implementation for Android" w/ JNI fixes for merge breakages

This reverts commit 5442c0a.

ci/licenses_golden/licenses_flutter

@@ -497,6 +497,8 @@ FILE: ../../../flutter/shell/platform/android/io/flutter/plugin/platform/Platfor
 FILE: ../../../flutter/shell/platform/android/io/flutter/plugin/platform/PlatformViewsController.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/plugin/platform/SingleViewPresentation.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/plugin/platform/VirtualDisplayController.java
+FILE: ../../../flutter/shell/platform/android/io/flutter/view/FlutterCallbackInformation.java
+FILE: ../../../flutter/shell/platform/android/io/flutter/view/FlutterRunArguments.java
 FILE: ../../../flutter/shell/platform/darwin/ios/framework/Headers/FlutterCallbackCache.h
 FILE: ../../../flutter/shell/platform/darwin/ios/framework/Headers/FlutterPluginAppLifeCycleDelegate.h
 FILE: ../../../flutter/shell/platform/darwin/ios/framework/Source/FlutterCallbackCache.mm

shell/platform/android/BUILD.gn

@@ -133,8 +133,10 @@ java_library("flutter_shell_java") {
     "io/flutter/util/PathUtils.java",
     "io/flutter/util/Preconditions.java",
     "io/flutter/view/AccessibilityBridge.java",
+    "io/flutter/view/FlutterCallbackInformation.java",
     "io/flutter/view/FlutterMain.java",
     "io/flutter/view/FlutterNativeView.java",
+    "io/flutter/view/FlutterRunArguments.java",
     "io/flutter/view/FlutterView.java",
     "io/flutter/view/ResourceCleaner.java",
     "io/flutter/view/ResourceExtractor.java",

shell/platform/android/android_shell_holder.cc

@@ -23,34 +23,51 @@ namespace shell {
 
 AndroidShellHolder::AndroidShellHolder(
     blink::Settings settings,
-    fml::jni::JavaObjectWeakGlobalRef java_object)
+    fml::jni::JavaObjectWeakGlobalRef java_object,
+    bool is_background_view)
     : settings_(std::move(settings)), java_object_(java_object) {
   static size_t shell_count = 1;
   auto thread_label = std::to_string(shell_count++);
 
   FML_CHECK(pthread_key_create(&thread_destruct_key_, ThreadDestructCallback) ==
             0);
 
-  thread_host_ = {thread_label, ThreadHost::Type::UI | ThreadHost::Type::GPU |
-                                    ThreadHost::Type::IO};
+  if (is_background_view) {
+    thread_host_ = {thread_label, ThreadHost::Type::UI};
+  } else {
+    thread_host_ = {thread_label, ThreadHost::Type::UI | ThreadHost::Type::GPU |
+                                      ThreadHost::Type::IO};
+  }
 
   // Detach from JNI when the UI and GPU threads exit.
   auto jni_exit_task([key = thread_destruct_key_]() {
     FML_CHECK(pthread_setspecific(key, reinterpret_cast<void*>(1)) == 0);
   });
   thread_host_.ui_thread->GetTaskRunner()->PostTask(jni_exit_task);
-  thread_host_.gpu_thread->GetTaskRunner()->PostTask(jni_exit_task);
+  if (!is_background_view) {
+    thread_host_.gpu_thread->GetTaskRunner()->PostTask(jni_exit_task);
+  }
 
   fml::WeakPtr<PlatformViewAndroid> weak_platform_view;
   Shell::CreateCallback<PlatformView> on_create_platform_view =
-      [java_object, &weak_platform_view](Shell& shell) {
-        auto platform_view_android = std::make_unique<PlatformViewAndroid>(
-            shell,                   // delegate
-            shell.GetTaskRunners(),  // task runners
-            java_object,             // java object handle for JNI interop
-            shell.GetSettings()
-                .enable_software_rendering  // use software rendering
-        );
+      [is_background_view, java_object, &weak_platform_view](Shell& shell) {
+        std::unique_ptr<PlatformViewAndroid> platform_view_android;
+        if (is_background_view) {
+          platform_view_android = std::make_unique<PlatformViewAndroid>(
+              shell,                   // delegate
+              shell.GetTaskRunners(),  // task runners
+              java_object              // java object handle for JNI interop
+          );
+
+        } else {
+          platform_view_android = std::make_unique<PlatformViewAndroid>(
+              shell,                   // delegate
+              shell.GetTaskRunners(),  // task runners
+              java_object,             // java object handle for JNI interop
+              shell.GetSettings()
+                  .enable_software_rendering  // use software rendering
+          );
+        }
         weak_platform_view = platform_view_android->GetWeakPtr();
         return platform_view_android;
       };
@@ -62,13 +79,26 @@ AndroidShellHolder::AndroidShellHolder(
   // The current thread will be used as the platform thread. Ensure that the
   // message loop is initialized.
   fml::MessageLoop::EnsureInitializedForCurrentThread();
-
-  blink::TaskRunners task_runners(
-      thread_label,                                    // label
-      fml::MessageLoop::GetCurrent().GetTaskRunner(),  // platform
-      thread_host_.gpu_thread->GetTaskRunner(),        // gpu
-      thread_host_.ui_thread->GetTaskRunner(),         // ui
-      thread_host_.io_thread->GetTaskRunner()          // io
+  fml::RefPtr<fml::TaskRunner> gpu_runner;
+  fml::RefPtr<fml::TaskRunner> ui_runner;
+  fml::RefPtr<fml::TaskRunner> io_runner;
+  fml::RefPtr<fml::TaskRunner> platform_runner =
+      fml::MessageLoop::GetCurrent().GetTaskRunner();
+  if (is_background_view) {
+    auto single_task_runner = thread_host_.ui_thread->GetTaskRunner();
+    gpu_runner = single_task_runner;
+    ui_runner = single_task_runner;
+    io_runner = single_task_runner;
+  } else {
+    gpu_runner = thread_host_.gpu_thread->GetTaskRunner();
+    ui_runner = thread_host_.ui_thread->GetTaskRunner();
+    io_runner = thread_host_.io_thread->GetTaskRunner();
+  }
+  blink::TaskRunners task_runners(thread_label,     // label
+                                  platform_runner,  // platform
+                                  gpu_runner,       // gpu
+                                  ui_runner,        // ui
+                                  io_runner         // io
   );
 
   shell_ =
@@ -131,10 +161,12 @@ void AndroidShellHolder::Launch(RunConfiguration config) {
       fml::MakeCopyable([engine = shell_->GetEngine(),  //
                          config = std::move(config)     //
   ]() mutable {
-        if (engine) {
-          if (!engine->Run(std::move(config))) {
-            FML_LOG(ERROR) << "Could not launch engine in configuration.";
-          }
+        FML_LOG(INFO) << "Attempting to launch engine configuration...";
+        if (!engine || !engine->Run(std::move(config))) {
+          FML_LOG(ERROR) << "Could not launch engine in configuration.";
+        } else {
+          FML_LOG(INFO) << "Isolate for engine configuration successfully "
+                           "started and run.";
         }
       }));
 }

shell/platform/android/android_shell_holder.h

@@ -21,7 +21,8 @@ namespace shell {
 class AndroidShellHolder {
  public:
   AndroidShellHolder(blink::Settings settings,
-                     fml::jni::JavaObjectWeakGlobalRef java_object);
+                     fml::jni::JavaObjectWeakGlobalRef java_object,
+                     bool is_background_view);
 
   ~AndroidShellHolder();
 

shell/platform/android/io/flutter/app/FlutterActivityDelegate.java

@@ -30,6 +30,7 @@
 import io.flutter.util.Preconditions;
 import io.flutter.view.FlutterMain;
 import io.flutter.view.FlutterNativeView;
+import io.flutter.view.FlutterRunArguments;
 import io.flutter.view.FlutterView;
 
 import java.util.ArrayList;
@@ -162,19 +163,16 @@ public void onCreate(Bundle savedInstanceState) {
             }
         }
 
-        // When an activity is created for the first time, we direct the
-        // FlutterView to re-use a pre-existing Isolate rather than create a new
-        // one. This is so that an Isolate coming in from the ViewFactory is
-        // used.
-        final boolean reuseIsolate = true;
-
-        if (loadIntent(activity.getIntent(), reuseIsolate)) {
+        if (loadIntent(activity.getIntent())) {
             return;
         }
         if (!flutterView.getFlutterNativeView().isApplicationRunning()) {
           String appBundlePath = FlutterMain.findAppBundlePath(activity.getApplicationContext());
           if (appBundlePath != null) {
-            flutterView.runFromBundle(appBundlePath, null, "main", reuseIsolate);
+            FlutterRunArguments arguments = new FlutterRunArguments();
+            arguments.bundlePath = appBundlePath;
+            arguments.entrypoint = "main";
+            flutterView.runFromBundle(arguments);
           }
         }
     }
@@ -325,11 +323,6 @@ private static String[] getArgsFromIntent(Intent intent) {
     }
 
     private boolean loadIntent(Intent intent) {
-        final boolean reuseIsolate = false;
-        return loadIntent(intent, reuseIsolate);
-    }
-
-    private boolean loadIntent(Intent intent, boolean reuseIsolate) {
         String action = intent.getAction();
         if (Intent.ACTION_RUN.equals(action)) {
             String route = intent.getStringExtra("route");
@@ -343,7 +336,10 @@ private boolean loadIntent(Intent intent, boolean reuseIsolate) {
                 flutterView.setInitialRoute(route);
             }
             if (!flutterView.getFlutterNativeView().isApplicationRunning()) {
-                flutterView.runFromBundle(appBundlePath, null, "main", reuseIsolate);
+              FlutterRunArguments args = new FlutterRunArguments();
+              args.bundlePath = appBundlePath;
+              args.entrypoint = "main";
+              flutterView.runFromBundle(args);
             }
             return true;
         }

shell/platform/android/io/flutter/view/FlutterCallbackInformation.java

@@ -0,0 +1,34 @@
+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package io.flutter.view;
+
+/**
+ * A class representing information for a callback registered using
+ * `PluginUtilities` from `dart:ui`.
+ */
+public final class FlutterCallbackInformation {
+  final public String callbackName;
+  final public String callbackClassName;
+  final public String callbackLibraryPath;
+
+  /**
+   * Get callback information for a given handle.
+   * @param handle the handle for the callback, generated by
+   * `PluginUtilities.getCallbackHandle` in `dart:ui`.
+   * @return an instance of FlutterCallbackInformation for the provided handle.
+   */
+  public static FlutterCallbackInformation lookupCallbackInformation(long handle) {
+    return nativeLookupCallbackInformation(handle);
+  }
+
+  private FlutterCallbackInformation(String callbackName,
+      String callbackClassName, String callbackLibraryPath) {
+    this.callbackName = callbackName;
+    this.callbackClassName = callbackClassName;
+    this.callbackLibraryPath = callbackLibraryPath;
+  }
+
+  private static native FlutterCallbackInformation nativeLookupCallbackInformation(long handle);
+}