From 05c9c3ff0100e6e2c342801abb59cfbd0691c5f1 Mon Sep 17 00:00:00 2001
From: jonahwilliams <jonahwilliams@google.com>
Date: Tue, 13 Jun 2023 12:29:31 -0700
Subject: [PATCH 1/2] finish out switches.

---
 shell/platform/android/context/android_context.h    |  3 +++
 .../embedding/engine/loader/FlutterLoader.java      |  6 ++++--
 shell/platform/android/platform_view_android.cc     | 13 +++++++++++--
 3 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/shell/platform/android/context/android_context.h b/shell/platform/android/context/android_context.h
index ac3b7d49dee8a..a967ca2451ace 100644
--- a/shell/platform/android/context/android_context.h
+++ b/shell/platform/android/context/android_context.h
@@ -16,6 +16,9 @@ enum class AndroidRenderingAPI {
   kSoftware,
   kOpenGLES,
   kVulkan,
+  /// @brief Attempt to create a Vulkan surface, if that fails then fall back
+  /// to GLES.
+  kAutoselect,
 };
 
 //------------------------------------------------------------------------------
diff --git a/shell/platform/android/io/flutter/embedding/engine/loader/FlutterLoader.java b/shell/platform/android/io/flutter/embedding/engine/loader/FlutterLoader.java
index fc5c9417e4190..8265cd46a8858 100644
--- a/shell/platform/android/io/flutter/embedding/engine/loader/FlutterLoader.java
+++ b/shell/platform/android/io/flutter/embedding/engine/loader/FlutterLoader.java
@@ -327,8 +327,10 @@ public void ensureInitializationComplete(
         if (metaData.getBoolean(ENABLE_VULKAN_VALIDATION_META_DATA_KEY, false)) {
           shellArgs.add("--enable-vulkan-validation");
         }
-        String backend = metaData.getString(IMPELLER_BACKEND_META_DATA_KEY, "opengles");
-        shellArgs.add("--impeller-backend=" + backend);
+        String backend = metaData.getString(IMPELLER_BACKEND_META_DATA_KEY);
+        if (backend != null) {
+          shellArgs.add("--impeller-backend=" + backend);
+        }
       }
 
       final String leakVM = isLeakVM(metaData) ? "true" : "false";
diff --git a/shell/platform/android/platform_view_android.cc b/shell/platform/android/platform_view_android.cc
index 7e8b10f778d03..e1b51127a5695 100644
--- a/shell/platform/android/platform_view_android.cc
+++ b/shell/platform/android/platform_view_android.cc
@@ -74,8 +74,8 @@ static std::shared_ptr<flutter::AndroidContext> CreateAndroidContext(
   if (enable_impeller) {
     // TODO(gaaclarke): We need to devise a more complete heuristic about what
     //                  backend to use by default.
-    // Default value is OpenGLES.
-    AndroidRenderingAPI backend = AndroidRenderingAPI::kOpenGLES;
+    // Default value is Vulkan with gles fallback.
+    AndroidRenderingAPI backend = AndroidRenderingAPI::kAutoselect;
     if (impeller_backend.has_value()) {
       if (impeller_backend.value() == "opengles") {
         backend = AndroidRenderingAPI::kOpenGLES;
@@ -93,6 +93,15 @@ static std::shared_ptr<flutter::AndroidContext> CreateAndroidContext(
       case AndroidRenderingAPI::kVulkan:
         return std::make_unique<AndroidContextVulkanImpeller>(
             enable_vulkan_validation, worker_task_runner);
+      case AndroidRenderingAPI::kAutoselect: {
+        auto vulkan_backend = std::make_unique<AndroidContextVulkanImpeller>(
+            enable_vulkan_validation, worker_task_runner);
+        if (!vulkan_backend->IsValid()) {
+          return std::make_unique<AndroidContextGLImpeller>(
+              std::make_unique<impeller::egl::Display>());
+        }
+        return vulkan_backend;
+      }
       default:
         FML_UNREACHABLE();
     }

From f4c9d008b297f87dd5b6d69613b65bd1eae1e7f1 Mon Sep 17 00:00:00 2001
From: jonahwilliams <jonahwilliams@google.com>
Date: Tue, 13 Jun 2023 12:34:37 -0700
Subject: [PATCH 2/2] ++

---
 shell/platform/android/platform_view_android.cc | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/shell/platform/android/platform_view_android.cc b/shell/platform/android/platform_view_android.cc
index e1b51127a5695..a1053fbcaaa13 100644
--- a/shell/platform/android/platform_view_android.cc
+++ b/shell/platform/android/platform_view_android.cc
@@ -72,9 +72,7 @@ static std::shared_ptr<flutter::AndroidContext> CreateAndroidContext(
     return std::make_shared<AndroidContext>(AndroidRenderingAPI::kSoftware);
   }
   if (enable_impeller) {
-    // TODO(gaaclarke): We need to devise a more complete heuristic about what
-    //                  backend to use by default.
-    // Default value is Vulkan with gles fallback.
+    // Default value is Vulkan with GLES fallback.
     AndroidRenderingAPI backend = AndroidRenderingAPI::kAutoselect;
     if (impeller_backend.has_value()) {
       if (impeller_backend.value() == "opengles") {