Implement external view embedder on Android (flutter#19033)

The external view embedder allows to embed Android views in a Flutter app.

BUILD.gn

@@ -74,7 +74,6 @@ group("flutter") {
       "//flutter/lib/ui:ui_unittests",
       "//flutter/runtime:runtime_unittests",
       "//flutter/shell/common:shell_unittests",
-      "//flutter/shell/platform/android/external_view_embedder:android_external_view_embedder_unittests",
       "//flutter/shell/platform/embedder:embedder_unittests",
       "//flutter/testing:testing_unittests",
       "//flutter/third_party/txt:txt_unittests",
@@ -85,6 +84,8 @@ group("flutter") {
         "//flutter/fml:fml_benchmarks",
         "//flutter/lib/ui:ui_benchmarks",
         "//flutter/shell/common:shell_benchmarks",
+        "//flutter/shell/platform/android/external_view_embedder:android_external_view_embedder_unittests",
+        "//flutter/shell/platform/android/jni:jni_unittests",
         "//flutter/third_party/txt:txt_benchmarks",
       ]
     }

ci/licenses_golden/licenses_flutter

@@ -645,21 +645,15 @@ FILE: ../../../flutter/shell/gpu/gpu_surface_vulkan.h
 FILE: ../../../flutter/shell/gpu/gpu_surface_vulkan_delegate.cc
 FILE: ../../../flutter/shell/gpu/gpu_surface_vulkan_delegate.h
 FILE: ../../../flutter/shell/platform/android/AndroidManifest.xml
-FILE: ../../../flutter/shell/platform/android/android_context.cc
-FILE: ../../../flutter/shell/platform/android/android_context.h
 FILE: ../../../flutter/shell/platform/android/android_context_gl.cc
 FILE: ../../../flutter/shell/platform/android/android_context_gl.h
 FILE: ../../../flutter/shell/platform/android/android_environment_gl.cc
 FILE: ../../../flutter/shell/platform/android/android_environment_gl.h
 FILE: ../../../flutter/shell/platform/android/android_exports.lst
 FILE: ../../../flutter/shell/platform/android/android_external_texture_gl.cc
 FILE: ../../../flutter/shell/platform/android/android_external_texture_gl.h
-FILE: ../../../flutter/shell/platform/android/android_native_window.cc
-FILE: ../../../flutter/shell/platform/android/android_native_window.h
 FILE: ../../../flutter/shell/platform/android/android_shell_holder.cc
 FILE: ../../../flutter/shell/platform/android/android_shell_holder.h
-FILE: ../../../flutter/shell/platform/android/android_surface.cc
-FILE: ../../../flutter/shell/platform/android/android_surface.h
 FILE: ../../../flutter/shell/platform/android/android_surface_gl.cc
 FILE: ../../../flutter/shell/platform/android/android_surface_gl.h
 FILE: ../../../flutter/shell/platform/android/android_surface_software.cc
@@ -668,9 +662,14 @@ FILE: ../../../flutter/shell/platform/android/android_surface_vulkan.cc
 FILE: ../../../flutter/shell/platform/android/android_surface_vulkan.h
 FILE: ../../../flutter/shell/platform/android/apk_asset_provider.cc
 FILE: ../../../flutter/shell/platform/android/apk_asset_provider.h
+FILE: ../../../flutter/shell/platform/android/context/android_context.cc
+FILE: ../../../flutter/shell/platform/android/context/android_context.h
 FILE: ../../../flutter/shell/platform/android/external_view_embedder/external_view_embedder.cc
 FILE: ../../../flutter/shell/platform/android/external_view_embedder/external_view_embedder.h
 FILE: ../../../flutter/shell/platform/android/external_view_embedder/external_view_embedder_unittests.cc
+FILE: ../../../flutter/shell/platform/android/external_view_embedder/surface_pool.cc
+FILE: ../../../flutter/shell/platform/android/external_view_embedder/surface_pool.h
+FILE: ../../../flutter/shell/platform/android/external_view_embedder/surface_pool_unittests.cc
 FILE: ../../../flutter/shell/platform/android/flutter_main.cc
 FILE: ../../../flutter/shell/platform/android/flutter_main.h
 FILE: ../../../flutter/shell/platform/android/io/flutter/Log.java
@@ -786,6 +785,8 @@ FILE: ../../../flutter/shell/platform/android/io/flutter/view/FlutterRunArgument
 FILE: ../../../flutter/shell/platform/android/io/flutter/view/FlutterView.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/view/TextureRegistry.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/view/VsyncWaiter.java
+FILE: ../../../flutter/shell/platform/android/jni/jni_mock.h
+FILE: ../../../flutter/shell/platform/android/jni/jni_mock_unittest.cc
 FILE: ../../../flutter/shell/platform/android/jni/platform_view_android_jni.cc
 FILE: ../../../flutter/shell/platform/android/jni/platform_view_android_jni.h
 FILE: ../../../flutter/shell/platform/android/library_loader.cc
@@ -796,6 +797,12 @@ FILE: ../../../flutter/shell/platform/android/platform_view_android.h
 FILE: ../../../flutter/shell/platform/android/platform_view_android_jni_impl.cc
 FILE: ../../../flutter/shell/platform/android/platform_view_android_jni_impl.h
 FILE: ../../../flutter/shell/platform/android/robolectric.properties
+FILE: ../../../flutter/shell/platform/android/surface/android_native_window.cc
+FILE: ../../../flutter/shell/platform/android/surface/android_native_window.h
+FILE: ../../../flutter/shell/platform/android/surface/android_surface.cc
+FILE: ../../../flutter/shell/platform/android/surface/android_surface.h
+FILE: ../../../flutter/shell/platform/android/surface/android_surface_mock.cc
+FILE: ../../../flutter/shell/platform/android/surface/android_surface_mock.h
 FILE: ../../../flutter/shell/platform/android/vsync_waiter_android.cc
 FILE: ../../../flutter/shell/platform/android/vsync_waiter_android.h
 FILE: ../../../flutter/shell/platform/common/cpp/client_wrapper/basic_message_channel_unittests.cc

flow/embedded_views.h

@@ -227,9 +227,11 @@ class ExternalViewEmbedder {
   // sets the stage for the next pre-roll.
   virtual void CancelFrame() = 0;
 
-  virtual void BeginFrame(SkISize frame_size,
-                          GrContext* context,
-                          double device_pixel_ratio) = 0;
+  virtual void BeginFrame(
+      SkISize frame_size,
+      GrContext* context,
+      double device_pixel_ratio,
+      fml::RefPtr<fml::RasterThreadMerger> raster_thread_merger) = 0;
 
   virtual void PrerollCompositeEmbeddedView(
       int view_id,

fml/raster_thread_merger.cc

@@ -28,12 +28,15 @@ void RasterThreadMerger::MergeWithLease(size_t lease_term) {
   }
 }
 
-bool RasterThreadMerger::IsOnRasterizingThread() {
-  const auto current_queue_id = MessageLoop::GetCurrentTaskQueueId();
+bool RasterThreadMerger::IsOnPlatformThread() const {
+  return MessageLoop::GetCurrentTaskQueueId() == platform_queue_id_;
+}
+
+bool RasterThreadMerger::IsOnRasterizingThread() const {
   if (is_merged_) {
-    return current_queue_id == platform_queue_id_;
+    return IsOnPlatformThread();
   } else {
-    return current_queue_id == gpu_queue_id_;
+    return !IsOnPlatformThread();
   }
 }
 

fml/raster_thread_merger.h

@@ -44,7 +44,10 @@ class RasterThreadMerger
   // Returns true if the current thread owns rasterizing.
   // When the threads are merged, platform thread owns rasterizing.
   // When un-merged, raster thread owns rasterizing.
-  bool IsOnRasterizingThread();
+  bool IsOnRasterizingThread() const;
+
+  // Returns true if the current thread is the platform thread.
+  bool IsOnPlatformThread() const;
 
  private:
   static const int kLeaseNotSet;

fml/raster_thread_merger_unittests.cc

@@ -92,12 +92,14 @@ TEST(RasterThreadMerger, IsNotOnRasterizingThread) {
 
   loop1->GetTaskRunner()->PostTask([&]() {
     ASSERT_FALSE(raster_thread_merger_->IsOnRasterizingThread());
+    ASSERT_TRUE(raster_thread_merger_->IsOnPlatformThread());
     ASSERT_EQ(fml::MessageLoop::GetCurrentTaskQueueId(), qid1);
     pre_merge.CountDown();
   });
 
   loop2->GetTaskRunner()->PostTask([&]() {
     ASSERT_TRUE(raster_thread_merger_->IsOnRasterizingThread());
+    ASSERT_FALSE(raster_thread_merger_->IsOnPlatformThread());
     ASSERT_EQ(fml::MessageLoop::GetCurrentTaskQueueId(), qid2);
     pre_merge.CountDown();
   });
@@ -108,6 +110,7 @@ TEST(RasterThreadMerger, IsNotOnRasterizingThread) {
 
   loop1->GetTaskRunner()->PostTask([&]() {
     ASSERT_TRUE(raster_thread_merger_->IsOnRasterizingThread());
+    ASSERT_TRUE(raster_thread_merger_->IsOnPlatformThread());
     ASSERT_EQ(fml::MessageLoop::GetCurrentTaskQueueId(), qid1);
     post_merge.CountDown();
   });
@@ -116,6 +119,7 @@ TEST(RasterThreadMerger, IsNotOnRasterizingThread) {
     // this will be false since this is going to be run
     // on loop1 really.
     ASSERT_TRUE(raster_thread_merger_->IsOnRasterizingThread());
+    ASSERT_TRUE(raster_thread_merger_->IsOnPlatformThread());
     ASSERT_EQ(fml::MessageLoop::GetCurrentTaskQueueId(), qid1);
     post_merge.CountDown();
   });
@@ -126,12 +130,14 @@ TEST(RasterThreadMerger, IsNotOnRasterizingThread) {
 
   loop1->GetTaskRunner()->PostTask([&]() {
     ASSERT_FALSE(raster_thread_merger_->IsOnRasterizingThread());
+    ASSERT_TRUE(raster_thread_merger_->IsOnPlatformThread());
     ASSERT_EQ(fml::MessageLoop::GetCurrentTaskQueueId(), qid1);
     post_unmerge.CountDown();
   });
 
   loop2->GetTaskRunner()->PostTask([&]() {
     ASSERT_TRUE(raster_thread_merger_->IsOnRasterizingThread());
+    ASSERT_FALSE(raster_thread_merger_->IsOnPlatformThread());
     ASSERT_EQ(fml::MessageLoop::GetCurrentTaskQueueId(), qid2);
     post_unmerge.CountDown();
   });

shell/common/rasterizer.cc

@@ -391,9 +391,9 @@ RasterStatus Rasterizer::DrawToSurface(flutter::LayerTree& layer_tree) {
 
   SkCanvas* embedder_root_canvas = nullptr;
   if (external_view_embedder != nullptr) {
-    external_view_embedder->BeginFrame(layer_tree.frame_size(),
-                                       surface_->GetContext(),
-                                       layer_tree.device_pixel_ratio());
+    external_view_embedder->BeginFrame(
+        layer_tree.frame_size(), surface_->GetContext(),
+        layer_tree.device_pixel_ratio(), raster_thread_merger_);
     embedder_root_canvas = external_view_embedder->GetRootCanvas();
   }
 

shell/common/shell_test_external_view_embedder.cc

@@ -6,9 +6,11 @@ namespace flutter {
 void ShellTestExternalViewEmbedder::CancelFrame() {}
 
 // |ExternalViewEmbedder|
-void ShellTestExternalViewEmbedder::BeginFrame(SkISize frame_size,
-                                               GrContext* context,
-                                               double device_pixel_ratio) {}
+void ShellTestExternalViewEmbedder::BeginFrame(
+    SkISize frame_size,
+    GrContext* context,
+    double device_pixel_ratio,
+    fml::RefPtr<fml::RasterThreadMerger> raster_thread_merger) {}
 
 // |ExternalViewEmbedder|
 void ShellTestExternalViewEmbedder::PrerollCompositeEmbeddedView(

shell/common/shell_test_external_view_embedder.h

@@ -29,9 +29,11 @@ class ShellTestExternalViewEmbedder final : public ExternalViewEmbedder {
   void CancelFrame() override;
 
   // |ExternalViewEmbedder|
-  void BeginFrame(SkISize frame_size,
-                  GrContext* context,
-                  double device_pixel_ratio) override;
+  void BeginFrame(
+      SkISize frame_size,
+      GrContext* context,
+      double device_pixel_ratio,
+      fml::RefPtr<fml::RasterThreadMerger> raster_thread_merger) override;
 
   // |ExternalViewEmbedder|
   void PrerollCompositeEmbeddedView(

shell/platform/android/BUILD.gn

@@ -23,20 +23,14 @@ shared_library("flutter_shell_native") {
 
   sources = [
     "$root_build_dir/flutter_icu/icudtl.o",
-    "android_context.cc",
-    "android_context.h",
     "android_context_gl.cc",
     "android_context_gl.h",
     "android_environment_gl.cc",
     "android_environment_gl.h",
     "android_external_texture_gl.cc",
     "android_external_texture_gl.h",
-    "android_native_window.cc",
-    "android_native_window.h",
     "android_shell_holder.cc",
     "android_shell_holder.h",
-    "android_surface.cc",
-    "android_surface.h",
     "android_surface_gl.cc",
     "android_surface_gl.h",
     "android_surface_software.cc",
@@ -67,8 +61,11 @@ shared_library("flutter_shell_native") {
     "//flutter/runtime",
     "//flutter/runtime:libdart",
     "//flutter/shell/common",
+    "//flutter/shell/platform/android/context",
     "//flutter/shell/platform/android/external_view_embedder",
     "//flutter/shell/platform/android/jni",
+    "//flutter/shell/platform/android/surface",
+    "//flutter/shell/platform/android/surface:native_window",
     "//third_party/skia",
   ]
 

shell/platform/android/android_context_gl.h

@@ -9,9 +9,9 @@
 #include "flutter/fml/memory/ref_counted.h"
 #include "flutter/fml/memory/ref_ptr.h"
 #include "flutter/shell/common/platform_view.h"
-#include "flutter/shell/platform/android/android_context.h"
 #include "flutter/shell/platform/android/android_environment_gl.h"
-#include "flutter/shell/platform/android/android_native_window.h"
+#include "flutter/shell/platform/android/context/android_context.h"
+#include "flutter/shell/platform/android/surface/android_native_window.h"
 #include "third_party/skia/include/core/SkSize.h"
 
 namespace flutter {

shell/platform/android/android_shell_holder.cc

@@ -16,6 +16,7 @@
 
 #include "flutter/fml/make_copyable.h"
 #include "flutter/fml/message_loop.h"
+#include "flutter/fml/platform/android/jni_util.h"
 #include "flutter/shell/common/rasterizer.h"
 #include "flutter/shell/platform/android/platform_view_android.h"
 

shell/platform/android/android_surface_gl.cc

@@ -13,19 +13,22 @@ namespace flutter {
 
 AndroidSurfaceGL::AndroidSurfaceGL(
     std::shared_ptr<AndroidContext> android_context,
-    std::shared_ptr<PlatformViewAndroidJNI> jni_facade)
-    : native_window_(nullptr),
+    std::shared_ptr<PlatformViewAndroidJNI> jni_facade,
+    const AndroidSurface::Factory& surface_factory)
+    : external_view_embedder_(
+          std::make_unique<AndroidExternalViewEmbedder>(android_context,
+                                                        jni_facade,
+                                                        surface_factory)),
+      android_context_(
+          std::static_pointer_cast<AndroidContextGL>(android_context)),
+      native_window_(nullptr),
       onscreen_surface_(nullptr),
       offscreen_surface_(nullptr) {
-  android_context_ =
-      std::static_pointer_cast<AndroidContextGL>(android_context);
   // Acquire the offscreen surface.
   offscreen_surface_ = android_context_->CreateOffscreenSurface();
   if (!offscreen_surface_->IsValid()) {
     offscreen_surface_ = nullptr;
   }
-  external_view_embedder_ =
-      std::make_unique<AndroidExternalViewEmbedder>(jni_facade);
 }
 
 AndroidSurfaceGL::~AndroidSurfaceGL() = default;