draft

Author: Chris Yang

common/settings.h

@@ -213,6 +213,8 @@ struct Settings {
   /// to log a timeline event that tracks the latency of engine startup.
   std::chrono::microseconds engine_start_timestamp = {};
 
+  bool use_embedded_view = false;
+
   std::string ToString() const;
 };
 

shell/platform/android/android_shell_holder.cc

@@ -101,28 +101,53 @@ AndroidShellHolder::AndroidShellHolder(
     ui_runner = thread_host_.ui_thread->GetTaskRunner();
     io_runner = thread_host_.io_thread->GetTaskRunner();
   }
-  flutter::TaskRunners task_runners(thread_label,     // label
-                                    platform_runner,  // platform
-                                    gpu_runner,       // raster
-                                    ui_runner,        // ui
-                                    io_runner         // io
-  );
-
-  shell_ =
+  if (settings.use_embedded_view) {
+    // Embedded views requires the gpu and the platform views to be the same.
+    // The plan is to eventually dynamically merge the threads when there's a
+    // platform view in the layer tree.
+    // For now we use a fixed thread configuration with the same thread used as the
+    // gpu and platform task runner.
+    // TODO(amirh/chinmaygarde): remove this, and dynamically change the thread configuration.
+    // https://github.com/flutter/flutter/issues/23975
+    // https://github.com/flutter/flutter/issues/59930
+    flutter::TaskRunners task_runners(thread_label,     // label
+                                      platform_runner,  // platform
+                                      platform_runner,       // raster
+                                      ui_runner,        // ui
+                                      io_runner         // io
+    );
+
+    shell_ =
       Shell::Create(task_runners,             // task runners
                     GetDefaultWindowData(),   // window data
                     settings_,                // settings
                     on_create_platform_view,  // platform view create callback
                     on_create_rasterizer      // rasterizer create callback
       );
+  } else {
+    flutter::TaskRunners task_runners(thread_label,     // label
+                                      platform_runner,  // platform
+                                      gpu_runner,       // raster
+                                      ui_runner,        // ui
+                                      io_runner         // io
+    );
+
+    shell_ =
+      Shell::Create(task_runners,             // task runners
+                    GetDefaultWindowData(),   // window data
+                    settings_,                // settings
+                    on_create_platform_view,  // platform view create callback
+                    on_create_rasterizer      // rasterizer create callback
+      );
+  }
 
   platform_view_ = weak_platform_view;
   FML_DCHECK(platform_view_);
 
   is_valid_ = shell_ != nullptr;
 
   if (is_valid_) {
-    task_runners.GetRasterTaskRunner()->PostTask([]() {
+    shell_->GetTaskRunners().GetRasterTaskRunner()->PostTask([]() {
       // Android describes -8 as "most important display threads, for
       // compositing the screen and retrieving input events". Conservatively
       // set the raster thread to slightly lower priority than it.
@@ -134,7 +159,7 @@ AndroidShellHolder::AndroidShellHolder(
         }
       }
     });
-    task_runners.GetUITaskRunner()->PostTask([]() {
+    shell_->GetTaskRunners().GetUITaskRunner()->PostTask([]() {
       if (::setpriority(PRIO_PROCESS, gettid(), -1) != 0) {
         FML_LOG(ERROR) << "Failed to set UI task runner priority";
       }

shell/platform/android/flutter_main.cc

@@ -63,7 +63,8 @@ void FlutterMain::Init(JNIEnv* env,
                        jstring kernelPath,
                        jstring appStoragePath,
                        jstring engineCachesPath,
-                       jlong initTimeMillis) {
+                       jlong initTimeMillis,
+                       jboolean useEmbeddedView) {
   std::vector<std::string> args;
   args.push_back("flutter");
   for (auto& arg : fml::jni::StringArrayToVector(env, jargs)) {
@@ -99,6 +100,8 @@ void FlutterMain::Init(JNIEnv* env,
     }
   }
 
+  settings.use_embedded_view = useEmbeddedView;
+
   settings.task_observer_add = [](intptr_t key, fml::closure callback) {
     fml::MessageLoop::GetCurrent().AddTaskObserver(key, std::move(callback));
   };
@@ -165,8 +168,7 @@ bool FlutterMain::Register(JNIEnv* env) {
   static const JNINativeMethod methods[] = {
       {
           .name = "nativeInit",
-          .signature = "(Landroid/content/Context;[Ljava/lang/String;Ljava/"
-                       "lang/String;Ljava/lang/String;Ljava/lang/String;J)V",
+          .signature = "(Landroid/content/Context;[Ljava/lang/String;Ljava/",
           .fnPtr = reinterpret_cast<void*>(&Init),
       },
       {

shell/platform/android/flutter_main.h

@@ -36,7 +36,8 @@ class FlutterMain {
                    jstring kernelPath,
                    jstring appStoragePath,
                    jstring engineCachesPath,
-                   jlong initTimeMillis);
+                   jlong initTimeMillis,
+                   jboolean useEmbeddedView);
 
   void SetupObservatoryUriCallback(JNIEnv* env);
 

shell/platform/android/io/flutter/embedding/engine/loader/FlutterLoader.java

@@ -201,7 +201,6 @@ public void ensureInitializationComplete(
               + applicationInfo.nativeLibraryDir
               + File.separator
               + DEFAULT_LIBRARY);
-
       if (args != null) {
         Collections.addAll(shellArgs, args);
       }
@@ -234,13 +233,18 @@ public void ensureInitializationComplete(
       }
 
       long initTimeMillis = SystemClock.uptimeMillis() - initStartTimestampMillis;
+
+      Bundle bundle = applicationInfo.metaData;
+      boolean use_embedded_view = bundle.getBoolean("io.flutter.embedded_views_preview");
+
       FlutterJNI.nativeInit(
           applicationContext,
           shellArgs.toArray(new String[0]),
           kernelPath,
           result.appStoragePath,
           result.engineCachesPath,
-          initTimeMillis);
+          initTimeMillis,
+          use_embedded_view);
 
       initialized = true;
     } catch (Exception e) {