Android: Support APK Java targets using @NativeMethods.

Currently, trying to use proxy natives in an APK target will result in
multiple copies of GEN_JNI.class being added to the final jar since:
  * The jni_processor creates a GEN_JNI for the library target it
    runs on
  * The java_library_impl inside the APK target also adds a GEN_JNI
    to the output .jar because the final JNI step is a srcjar_dep

APK targets now support the annotation_processor_deps and
processor_args_javac args and must provide
"org.chromium.chrome.skipGenJni" to use proxy natives.

This CL also converts chromium_linker_test_apk__apk to use
annotation_processor_deps directly instead of the workaround added
in http://crrev.com/c/1758655.

Bug: 1001595
Change-Id: Ifb31b7c52327b2793540142eb013d0c39cb6435e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1842297Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Commit-Queue: Eric Stevenson <estevenson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#706955}

base/android/jni_generator/config.gni

+# Copyright 2019 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.
+
+# Including this is an android_apk's processor_args_javac list will result in
+# the JNI processor not writing a dummy GEN_JNI class. This is required when
+# using proxy natives in android_apk targets.
+skip_gen_jni_arg = "org.chromium.chrome.skipGenJni"

base/android/jni_generator/java/src/org/chromium/jni_generator/JniProcessor.java

@@ -36,6 +36,7 @@ import javax.annotation.Generated;
 import javax.annotation.processing.AbstractProcessor;
 import javax.annotation.processing.Processor;
 import javax.annotation.processing.RoundEnvironment;
+import javax.annotation.processing.SupportedOptions;
 import javax.lang.model.SourceVersion;
 import javax.lang.model.element.Element;
 import javax.lang.model.element.ElementKind;
@@ -58,8 +59,10 @@ import javax.tools.Diagnostic;
  * containing an interface annotated with NativeMethods.
  *
  */
+@SupportedOptions({JniProcessor.SKIP_GEN_JNI_ARG})
 @AutoService(Processor.class)
 public class JniProcessor extends AbstractProcessor {
+    static final String SKIP_GEN_JNI_ARG = "org.chromium.chrome.skipGenJni";
     private static final Class<NativeMethods> JNI_STATIC_NATIVES_CLASS = NativeMethods.class;
     private static final Class<MainDex> MAIN_DEX_CLASS = MainDex.class;
 
@@ -209,11 +212,14 @@ public class JniProcessor extends AbstractProcessor {
 
         try {
             // Need to write NativeClass first because the wrapper classes
-            // depend on it.
-            JavaFile nativeClassFile =
-                    JavaFile.builder(mNativeClassPackage, mNativesBuilder.build()).build();
+            // depend on it. This step is skipped for APK targets since the final GEN_JNI class is
+            // provided elsewhere.
+            if (!processingEnv.getOptions().containsKey(SKIP_GEN_JNI_ARG)) {
+                JavaFile nativeClassFile =
+                        JavaFile.builder(mNativeClassPackage, mNativesBuilder.build()).build();
 
-            nativeClassFile.writeTo(processingEnv.getFiler());
+                nativeClassFile.writeTo(processingEnv.getFiler());
+            }
 
             for (JavaFile f : writeQueue) {
                 f.writeTo(processingEnv.getFiler());

build/config/android/rules.gni

@@ -2140,6 +2140,10 @@ if (enable_java_templates) {
   #     LocaleConfig.java file will be generated for each package, and will
   #     contain the list of compressed and uncompressed locale pak files.
   #   disable_r8_outlining: Turn off outlining during the proguard step.
+  #   annotation_processor_deps: List of java_annotation_processor targets to
+  #     use when compiling the java_files given to this target (optional).
+  #   processor_args_javac: List of args to pass to annotation processors when
+  #     compiling java_files given to this target (optional).
   template("android_apk_or_module") {
     forward_variables_from(invoker, [ "testonly" ])
     assert(defined(invoker.android_manifest))
@@ -2773,10 +2777,10 @@ if (enable_java_templates) {
                                "alternative_android_sdk_dep",
                                "android_manifest",
                                "android_manifest_dep",
+                               "annotation_processor_deps",
                                "apk_under_test",
                                "base_module_target",
                                "chromium_code",
-                               "classpath_deps",
                                "jacoco_never_instrument",
                                "java_files",
                                "javac_args",
@@ -2784,6 +2788,7 @@ if (enable_java_templates) {
                                "manifest_package",
                                "native_lib_placeholders",
                                "no_build_hooks",
+                               "processor_args_javac",
                                "secondary_abi_loadable_modules",
                                "secondary_native_lib_placeholders",
                                "static_library_dependent_targets",
@@ -3365,6 +3370,7 @@ if (enable_java_templates) {
                                "alternative_android_sdk_dep",
                                "android_manifest",
                                "android_manifest_dep",
+                               "annotation_processor_deps",
                                "apk_under_test",
                                "app_as_shared_lib",
                                "build_hooks_android_impl_deps",
@@ -3407,6 +3413,7 @@ if (enable_java_templates) {
                                "no_xml_namespaces",
                                "png_to_webp",
                                "post_process_package_resources_script",
+                               "processor_args_javac",
                                "product_version_resources_dep",
                                "proguard_configs",
                                "proguard_enabled",
@@ -3497,6 +3504,7 @@ if (enable_java_templates) {
                                "alternative_android_sdk_dep",
                                "android_manifest",
                                "android_manifest_dep",
+                               "annotation_processor_deps",
                                "app_as_shared_lib",
                                "base_module_target",
                                "bundle_target",
@@ -3529,6 +3537,7 @@ if (enable_java_templates) {
                                "package_id",
                                "package_name",
                                "png_to_webp",
+                               "processor_args_javac",
                                "product_version_resources_dep",
                                "proguard_configs",
                                "proguard_enabled",

content/shell/android/BUILD.gn

@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//base/android/jni_generator/config.gni")
 import("//build/config/android/config.gni")
 import("//build/config/android/rules.gni")
 import("//third_party/icu/config.gni")
@@ -266,8 +267,12 @@ if (current_cpu != "x64") {
     testonly = true
     deps = [
       ":content_shell_assets",
+      ":content_shell_java",
       ":linker_resources",
-      ":linker_test_apk_all_java",
+      "//base:base_java",
+      "//base:jni_java",
+      "//content/public/android:content_java",
+      "//ui/android:ui_java",
     ]
     android_manifest = chromium_linker_test_manifest
     android_manifest_dep = ":chromium_linker_test_manifest"
@@ -276,24 +281,13 @@ if (current_cpu != "x64") {
     use_chromium_linker = true
     enable_chromium_linker_tests = true
     jni_registration_header = _linker_test_jni_registration_header
-  }
-
-  android_library("linker_test_apk_all_java") {
-    testonly = true
-    deps = [
-      ":content_shell_java",
-      ":linker_resources",
-      "//base:base_java",
-      "//base:jni_java",
-      "//content/public/android:content_java",
-      "//ui/android:ui_java",
-    ]
     java_files = [
       "linker_test_apk/src/org/chromium/chromium_linker_test_apk/ChromiumLinkerTestActivity.java",
       "linker_test_apk/src/org/chromium/chromium_linker_test_apk/ChromiumLinkerTestApplication.java",
       "linker_test_apk/src/org/chromium/chromium_linker_test_apk/LinkerTests.java",
     ]
     annotation_processor_deps = [ "//base/android/jni_generator:jni_processor" ]
+    processor_args_javac = [ skip_gen_jni_arg ]
   }
 
   test_runner_script(_linker_test_apk_test_runner_target_name) {