Enable Java impls for Cobalt's Mojo interfaces (youtube#4909)

A Java implementation for the CrashAnnotator interface is added as an
example. It is still stubbed, but now in Java; a quick follow-up will
implement it using StarboardBridge.setCrashContext.

The Mojo Java Bindings API doc was used as a reference.

b/383301493

build/build_config.h

@@ -296,6 +296,12 @@
 #define BUILDFLAG_INTERNAL_ENABLE_COBALT_HACKS() (0)
 #endif
 
+#if defined(ENABLE_BUILFLAG_IS_ANDROIDTV)
+#define BUILDFLAG_INTERNAL_IS_ANDROIDTV() (1)
+#else
+#define BUILDFLAG_INTERNAL_IS_ANDROIDTV() (0)
+#endif
+
 // Compiler detection. Note: clang masquerades as GCC on POSIX and as MSVC on
 // Windows.
 #if defined(__GNUC__)

cobalt/android/BUILD.gn

@@ -1,5 +1,6 @@
 import("//build/config/android/config.gni")
 import("//build/config/android/rules.gni")
+import("//starboard/build/buildflags.gni")
 import("//third_party/icu/config.gni")
 
 cobalt_manifest = "$target_gen_dir/cobalt_manifest/AndroidManifest.xml"
@@ -39,6 +40,12 @@ generate_jni("jni_headers") {
     "apk/app/src/main/java/dev/cobalt/coat/StarboardBridge.java",
     "apk/app/src/main/java/dev/cobalt/media/MediaCodecBridge.java",
   ]
+
+  if (!use_evergreen) {
+    sources += [
+      "apk/app/src/main/java/dev/cobalt/browser/CobaltInterfaceRegistrar.java",
+    ]
+  }
 }
 
 generate_jni("content_shell_jni_headers") {
@@ -130,6 +137,17 @@ android_library("cobalt_main_java") {
     "//ui/android:ui_no_recycler_view_java",
     "//url:gurl_java",
   ]
+
+  if (!use_evergreen) {
+    deps += [
+      "//cobalt/browser/crash_annotator/public/mojom:mojom_java",
+      "//mojo/public/java:base_java",
+      "//mojo/public/java:bindings_java",
+      "//mojo/public/java:system_java",
+      "//services/service_manager/public/java:service_manager_java",
+    ]
+  }
+
   sources = [
     "apk/app/src/main/java/dev/cobalt/coat/ArtworkDownloader.java",
     "apk/app/src/main/java/dev/cobalt/coat/ArtworkDownloaderDefault.java",
@@ -183,6 +201,14 @@ android_library("cobalt_main_java") {
     "apk/app/src/main/java/dev/cobalt/util/UsedByNative.java",
   ]
 
+  if (!use_evergreen) {
+    sources += [
+      "apk/app/src/main/java/dev/cobalt/browser/CobaltInterfaceRegistrar.java",
+      "apk/app/src/main/java/dev/cobalt/browser/crashannotator/CrashAnnotatorImpl.java",
+      "apk/app/src/main/java/dev/cobalt/browser/crashannotator/CrashAnnotatorImplFactory.java",
+    ]
+  }
+
   annotation_processor_deps = [ "//base/android/jni_generator:jni_processor" ]
 }
 

cobalt/android/apk/app/src/main/java/dev/cobalt/browser/CobaltInterfaceRegistrar.java

@@ -0,0 +1,43 @@
+// Copyright 2025 The Cobalt Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package dev.cobalt.browser;
+
+import dev.cobalt.browser.crashannotator.CrashAnnotatorImplFactory;
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.content_public.browser.InterfaceRegistrar;
+import org.chromium.content_public.browser.RenderFrameHost;
+import org.chromium.crashannotator.mojom.CrashAnnotator;
+import org.chromium.services.service_manager.InterfaceRegistry;
+
+/** Registers Mojo interface implementations exposed to C++ code at the Cobalt layer. */
+class CobaltInterfaceRegistrar {
+    @CalledByNative
+    private static void registerMojoInterfaces() {
+        InterfaceRegistrar.Registry.addRenderFrameHostRegistrar(
+            new CobaltRenderFrameHostInterfaceRegistrar());
+    }
+
+    private static class CobaltRenderFrameHostInterfaceRegistrar
+            implements InterfaceRegistrar<RenderFrameHost> {
+        @Override
+        public void registerInterfaces(
+                InterfaceRegistry registry,
+                final RenderFrameHost renderFrameHost) {
+            registry.addInterface(
+                CrashAnnotator.MANAGER,
+                new CrashAnnotatorImplFactory(renderFrameHost));
+        }
+    }
+}

cobalt/android/apk/app/src/main/java/dev/cobalt/browser/crashannotator/CrashAnnotatorImpl.java

@@ -0,0 +1,51 @@
+// Copyright 2025 The Cobalt Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package dev.cobalt.browser.crashannotator;
+
+import static dev.cobalt.util.Log.TAG;
+
+import dev.cobalt.util.Log;
+import org.chromium.content_public.browser.RenderFrameHost;
+import org.chromium.crashannotator.mojom.CrashAnnotator;
+import org.chromium.mojo.system.MojoException;
+
+/** Implements the CrashAnnotator Mojo interface in Java. */
+public class CrashAnnotatorImpl implements CrashAnnotator {
+    // TODO(cobalt, b/383301493): confirm that this member is needed for proper
+    // lifetime management.
+    private final RenderFrameHost mRenderFrameHost;
+
+    public CrashAnnotatorImpl(RenderFrameHost renderFrameHost) {
+        mRenderFrameHost = renderFrameHost;
+    }
+
+    @Override
+    public void setString(String key,
+                          String value,
+                          SetString_Response callback) {
+        // TODO(cobalt, b/383301493): actually implement this by calling
+        // StarboardBridge.setCrashContext().
+        Log.i(TAG, "Java CrashAnnotator impl key=%s value=%s", key, value);
+        callback.call(false);
+    }
+
+    /** This abstract method must be overridden. */
+    @Override
+    public void close() {}
+
+    /** This abstract method must be overridden. */
+    @Override
+    public void onConnectionError(MojoException e) {}
+}

cobalt/android/apk/app/src/main/java/dev/cobalt/browser/crashannotator/CrashAnnotatorImplFactory.java

@@ -0,0 +1,33 @@
+// Copyright 2025 The Cobalt Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package dev.cobalt.browser.crashannotator;
+
+import org.chromium.content_public.browser.RenderFrameHost;
+import org.chromium.crashannotator.mojom.CrashAnnotator;
+import org.chromium.services.service_manager.InterfaceFactory;
+
+/** Creates instances of CrashAnnotator Mojo interface implementations. */
+public class CrashAnnotatorImplFactory implements InterfaceFactory {
+    private final RenderFrameHost mRenderFrameHost;
+
+    public CrashAnnotatorImplFactory(RenderFrameHost renderFrameHost) {
+        mRenderFrameHost = renderFrameHost;
+    }
+
+    @Override
+    public CrashAnnotator createImpl() {
+        return new CrashAnnotatorImpl(mRenderFrameHost);
+    }
+}

cobalt/browser/BUILD.gn

@@ -12,6 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import("//starboard/build/buildflags.gni")
+
 source_set("browser") {
   # TODO(cobalt, b/375655377): remove testonly declaration, needed because of
   # content_shell_lib.
@@ -26,9 +28,15 @@ source_set("browser") {
     "cobalt_web_contents_observer.h",
   ]
 
+  if (is_androidtv) {
+    sources += [
+      "android/mojo/cobalt_interface_registrar_android.cc",
+      "android/mojo/cobalt_interface_registrar_android.h",
+    ]
+  }
+
   deps = [
     ":embed_polyfilled_javascript",
-    "//cobalt/browser/crash_annotator",
     "//cobalt/browser/crash_annotator/public/mojom",
     "//cobalt/browser/h5vcc_runtime",
     "//cobalt/browser/h5vcc_runtime/public/mojom",
@@ -39,6 +47,12 @@ source_set("browser") {
     "//content/public/browser",
     "//content/shell:content_shell_lib",
   ]
+
+  if (is_androidtv) {
+    deps += [ "//cobalt/android:jni_headers" ]
+  } else {
+    deps += [ "//cobalt/browser/crash_annotator" ]
+  }
 }
 
 config("embed_polyfilled_javascript_config") {

cobalt/browser/android/mojo/cobalt_interface_registrar_android.cc

@@ -0,0 +1,31 @@
+// Copyright 2025 The Cobalt Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "cobalt/browser/android/mojo/cobalt_interface_registrar_android.h"
+
+#include <jni.h>
+
+#include "base/android/jni_android.h"
+
+// Must come after all headers that specialize FromJniType() / ToJniType().
+#include "cobalt/android/jni_headers/CobaltInterfaceRegistrar_jni.h"
+
+namespace cobalt {
+
+void RegisterCobaltJavaMojoInterfaces() {
+  Java_CobaltInterfaceRegistrar_registerMojoInterfaces(
+      base::android::AttachCurrentThread());
+}
+
+}  // namespace cobalt

cobalt/browser/android/mojo/cobalt_interface_registrar_android.h

@@ -0,0 +1,25 @@
+// Copyright 2025 The Cobalt Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef COBALT_BROWSER_ANDROID_MOJO_COBALT_INTERFACE_REGISTRAR_ANDROID_H_
+#define COBALT_BROWSER_ANDROID_MOJO_COBALT_INTERFACE_REGISTRAR_ANDROID_H_
+
+namespace cobalt {
+
+// Registers Cobalt's Java Mojo interfaces with its independent registrar.
+void RegisterCobaltJavaMojoInterfaces();
+
+}  // namespace cobalt
+
+#endif  // COBALT_BROWSER_ANDROID_MOJO_COBALT_INTERFACE_REGISTRAR_ANDROID_H_

cobalt/browser/cobalt_browser_interface_binders.cc

@@ -15,20 +15,40 @@
 #include "cobalt/browser/cobalt_browser_interface_binders.h"
 
 #include "base/functional/bind.h"
-#include "cobalt/browser/crash_annotator/crash_annotator_impl.h"
 #include "cobalt/browser/crash_annotator/public/mojom/crash_annotator.mojom.h"
 #include "cobalt/browser/h5vcc_runtime/h5vcc_runtime_impl.h"
 #include "cobalt/browser/h5vcc_runtime/public/mojom/h5vcc_runtime.mojom.h"
 #include "cobalt/browser/h5vcc_system/h5vcc_system_impl.h"
 #include "cobalt/browser/h5vcc_system/public/mojom/h5vcc_system.mojom.h"
 
+#if BUILDFLAG(IS_ANDROIDTV)
+#include "content/public/browser/render_frame_host.h"
+#include "services/service_manager/public/cpp/interface_provider.h"
+#else
+#include "cobalt/browser/crash_annotator/crash_annotator_impl.h"
+#endif  // BUILDFLAG(IS_ANDROIDTV)
+
 namespace cobalt {
 
+#if BUILDFLAG(IS_ANDROIDTV)
+template <typename Interface>
+void ForwardToJavaFrame(content::RenderFrameHost* render_frame_host,
+                        mojo::PendingReceiver<Interface> receiver) {
+  render_frame_host->GetJavaInterfaces()->GetInterface(std::move(receiver));
+}
+#endif  // BUILDFLAG(IS_ANDROIDTV)
+
 void PopulateCobaltFrameBinders(
     content::RenderFrameHost* render_frame_host,
     mojo::BinderMapWithContext<content::RenderFrameHost*>* binder_map) {
+// We want to use the Java Mojo implementation for 1P ATV only.
+#if BUILDFLAG(IS_ANDROIDTV)
+  binder_map->Add<crash_annotator::mojom::CrashAnnotator>(base::BindRepeating(
+      &ForwardToJavaFrame<crash_annotator::mojom::CrashAnnotator>));
+#else
   binder_map->Add<crash_annotator::mojom::CrashAnnotator>(
       base::BindRepeating(&crash_annotator::CrashAnnotatorImpl::Create));
+#endif  // BUILDFLAG(IS_ANDROIDTV)
   binder_map->Add<h5vcc_system::mojom::H5vccSystem>(
       base::BindRepeating(&h5vcc_system::H5vccSystemImpl::Create));
   binder_map->Add<h5vcc_runtime::mojom::H5vccRuntime>(

cobalt/browser/cobalt_content_browser_client.cc

@@ -26,6 +26,10 @@
 
 #include "base/logging.h"
 
+#if BUILDFLAG(IS_ANDROIDTV)
+#include "cobalt/browser/android/mojo/cobalt_interface_registrar_android.h"
+#endif
+
 namespace cobalt {
 
 // TODO(b/390021478): When CobaltContentBrowserClient stops deriving from
@@ -45,6 +49,19 @@ class CobaltBrowserMainParts : public content::ShellBrowserMainParts {
     // when called from ChromeBrowserMainParts::PreCreateThreadsImpl().
     return ShellBrowserMainParts::PreCreateThreads();
   }
+
+// TODO(cobalt, b/383301493): we should consider moving any ATV-specific
+// behaviors into an ATV implementation of BrowserMainParts. For example, see
+// Chrome's ChromeBrowserMainPartsAndroid.
+#if BUILDFLAG(IS_ANDROIDTV)
+  void PostCreateThreads() override {
+    // TODO(cobalt, b/383301493): this looks like a reasonable stage at which to
+    // register these interfaces and it seems to work. But we may want to
+    // consider if there's a more suitable stage.
+    RegisterCobaltJavaMojoInterfaces();
+    ShellBrowserMainParts::PostCreateThreads();
+  }
+#endif  // BUILDFLAG(IS_ANDROIDTV)
 };
 
 std::string GetCobaltUserAgent() {

cobalt/browser/crash_annotator/public/mojom/BUILD.gn

@@ -15,5 +15,6 @@
 import("//mojo/public/tools/bindings/mojom.gni")
 
 mojom("mojom") {
+  generate_java = true
   sources = [ "crash_annotator.mojom" ]
 }

cobalt/browser/crash_annotator/public/mojom/crash_annotator.mojom

@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+[JavaPackage="org.chromium.crashannotator.mojom"]
 module crash_annotator.mojom;
 
 // The browser process must provide an implementation of this interface so that

cobalt/build/configs/BUILD.gn

@@ -66,4 +66,7 @@ config("buildflag_defines") {
   if (enable_cobalt_hacks) {
     defines += [ "ENABLE_BUILDFLAG_ENABLE_COBALT_HACKS" ]
   }
+  if (is_androidtv) {
+    defines += [ "ENABLE_BUILFLAG_IS_ANDROIDTV" ]
+  }
 }

starboard/build/buildflags.gni

@@ -4,3 +4,6 @@ declare_args() {
   use_starboard_media = is_cobalt
   use_evergreen = false
 }
+
+# Differentiates our 1P ATV platform from 3P AOSP.
+is_androidtv = is_android && !use_evergreen