GN: Enable loading libraries from apks

build/config/android/rules.gni

Index: build/config/android/rules.gni
diff --git a/build/config/android/rules.gni b/build/config/android/rules.gni
index af493bd9ff74a76276959e95a1ddc7feb13288fe..2bb432d4dc888710365a8c4254d65fb5facd5e52 100644
--- a/build/config/android/rules.gni
+++ b/build/config/android/rules.gni
@@ -626,6 +626,68 @@ template("android_library") {
   }
 }
 
+template("java_library") {
+  if (defined(invoker.testonly)) { testonly = invoker.testonly }
+
+  assert(defined(invoker.java_files) || defined(invoker.DEPRECATED_java_in_dir)
+      || defined(invoker.srcjars))
+
+  _srcjar_deps = []
+  if (defined(invoker.srcjar_deps)) {
+    _srcjar_deps = invoker.srcjar_deps
+  }
+
+  _srcjars = []
+  if (defined(invoker.srcjars)) {
+    _srcjars = invoker.srcjars
+  }
+
+  _java_files = []
+  if (defined(invoker.java_files)) {
+    _java_files = invoker.java_files
+  } else if (defined(invoker.DEPRECATED_java_in_dir)) {
+    _src_dir = invoker.DEPRECATED_java_in_dir + "/src"
+    _src_dir_exists = exec_script("//build/dir_exists.py",
+          [ rebase_path(_src_dir, root_build_dir) ],
+          "string")
+    assert(_src_dir_exists == "False",
+        "In GN, java_in_dir should be the fully specified java directory " +
+        "(i.e. including the trailing \"/src\")")
+
+    _java_files_build_rel = exec_script(
+        "//build/android/gyp/find.py",
+        [
+          "--pattern",
+          "*.java",
+          rebase_path(invoker.DEPRECATED_java_in_dir, root_build_dir)
+        ],
+        "list lines"
+        )
+    _java_files = rebase_path(_java_files_build_rel, ".", root_build_dir)
+  }
+  assert(_java_files != [] || _srcjar_deps != [] || _srcjars != [])
+
+  # TODO(cjhopman): Write a proper build config so that java library
+  # dependencies work correctly.
+  _build_config = "$target_gen_dir/$target_name.build_config"
+  write_file(
+      _build_config,
+      "{ \"javac\": { \"classpath\": [], \"srcjars\": [] } }")
+
+  _jar_path = "$root_build_dir/lib.java/$target_name.jar"
+  if (defined(invoker.jar_path)) {
+    _jar_path = invoker.jar_path
+  }
+
+  compile_java(target_name) {
+    build_config = _build_config
+    jar_path = _jar_path
+    java_files = _java_files
+    srcjar_deps = _srcjar_deps
+    srcjars = _srcjars
+  }
+}
+
 
 # Declare an Android library target for a prebuilt jar
 #
@@ -768,27 +830,16 @@ template("android_apk") {
   _dist_jar_path = _dist_jar_path_list[0]
 
   _native_libs = []
-  if (defined(invoker.native_libs)) {
-    _use_chromium_linker = false
-    if (defined(invoker.use_chromium_linker)) {
-      _use_chromium_linker = invoker.use_chromium_linker
-    }
 
-    # TODO(GYP) add "|| profiling_full_stack_frames
-    # Only enable the chromium linker on regular builds, since the
-    # component build crashes on Android 4.4. See b/11379966
-    if (is_component_build || cpu_arch == "arm64" || cpu_arch == "x64") {
-      _use_chromium_linker = false
-    }
-
-    _native_libs = invoker.native_libs
-    _native_libs_dir = base_path + "/libs"
+  _use_chromium_linker = false
+  if (defined(invoker.use_chromium_linker)) {
+    _use_chromium_linker = invoker.use_chromium_linker
+  }
+  assert(_use_chromium_linker || true)

[rmcilroy, 2014/10/21 10:55:45]

I'm not sure what this is testing?

[cjhopman, 2014/10/21 17:28:52]

Eh, this just marks _use_chromium_linker as "used" so that gn doesn't complain
if nothing below uses it. I've moved the variable into something guarded so that
it's always used.

 
-    if (_use_chromium_linker) {
-      _native_libs += [
-        "$root_build_dir/lib.stripped/libchromium_android_linker.so"
-      ]
-    }
+  _load_library_from_apk = false
+  if (defined(invoker.load_library_from_apk)) {
+    _load_library_from_apk = invoker.load_library_from_apk
   }
 
   _keystore_path = android_default_keystore_path
@@ -806,6 +857,24 @@ template("android_apk") {
     _srcjar_deps += invoker.srcjar_deps
   }
 
+  if (defined(invoker.native_libs)) {
+    # TODO(GYP) add "|| profiling_full_stack_frames
+    # Only enable the chromium linker on regular builds, since the
+    # component build crashes on Android 4.4. See b/11379966
+    if (is_component_build || cpu_arch == "arm64" || cpu_arch == "x64") {

[rmcilroy, 2014/10/21 10:55:45]

I realize you only moved this, but we still want _use_chromium_linker for arm64
and x64 (they are enabled in gyp now).

[cjhopman, 2014/10/21 17:28:52]

Done. It is not enabled in upstream targets for arm64/x64 in gyp, afaict though
(see chrome/chrome_android.gypi).

I've moved the concept of whether the linker is supported into it's own
config.gni file so that we don't end up with similar inconsistencies in GN.

[rmcilroy, 2014/10/21 21:21:03]

You are right, I was thinking of downstream.  Thanks for changing this.  I'm not
super familiar with the gyp/gn transition, but do you need to include
chromium_linker_supported in chrome_android.gypi in order to keep gyp/gn
consistant, or does the use of it in rules.gni do this?  If not, could you
update chrome_android.gypi to remove the cpu_arch conditions?

I think it should be consistent upstream and downstream, but adding simonb just
in case there was a reason for this.

[cjhopman, 2014/10/22 21:44:07]

In gyp we could do something similar... it would look like:

calculate chromium_linker_supported in some linker_config.gypi (or, as is
typical in gyp, build/common.gypi)
use that in java_apk.gypi and turn off the linker when it's not supported
targets that want to use the linker then just enable without calculating on
their own whether the linker is supported (though they could feel free to use
the flag).

I think that would be a little better than what we are doing now, but didn't
feel strongly enough to make that change in gyp myself. I want the GN build
rules, though, to sort of start off with good practices as examples.

+      _use_chromium_linker = false
+    }
+
+    _native_libs = invoker.native_libs
+    _native_libs_dir = base_path + "/libs"
+
+    if (_use_chromium_linker) {
+      _native_libs += [
+        "$root_build_dir/lib.stripped/libchromium_android_linker.so"
+      ]
+    }
+  }
+
   _rebased_build_config = rebase_path(build_config, root_build_dir)
 
   write_build_config("${_template_name}__build_config") {
@@ -838,7 +907,6 @@ template("android_apk") {
       _enable_chromium_linker_tests = invoker.enable_chromium_linker_tests
     }
 
-    _load_library_from_apk = false
     _native_lib_version_name = ""
 
     java_cpp_template("${_template_name}__native_libraries_java") {
@@ -942,6 +1010,7 @@ template("android_apk") {
     android_manifest = invoker.android_manifest
     resources_zip = all_resources_zip_path
     dex_path = final_dex_path
+    load_library_from_apk = _load_library_from_apk
 
     if (defined(invoker.asset_location)) {
       asset_location = invoker.asset_location