Android: Add use_java_goma GN arg for moving javac to goma

Bug: 726475
Change-Id: I6cc99d0d721c1f94203d2b9461e72ce2239b6a80
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2029261
Auto-Submit: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Simon Que <sque@chromium.org>
Reviewed-by: Peter Wen <wnwen@chromium.org>
Commit-Queue: Peter Wen <wnwen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#736837}

build/android/gyp/compile_java.py

@@ -513,6 +513,8 @@ def _ParseOptions(argv):
       type='int',
       help='Whether code being compiled should be built with stricter '
       'warnings for chromium code.')
+  parser.add_option(
+      '--gomacc-path', help='When set, prefix javac command with gomacc')
   parser.add_option(
       '--errorprone-path', help='Use the Errorprone compiler at this path.')
   parser.add_option(
@@ -566,7 +568,11 @@ def main(argv):
   options, java_files = _ParseOptions(argv)
   javac_path = build_utils.JAVAC_PATH
 
-  javac_cmd = [
+  javac_cmd = []
+  if options.gomacc_path:
+    javac_cmd.append(options.gomacc_path)
+
+  javac_cmd += [
       javac_path,
       '-g',
       # Chromium only allows UTF8 source files.  Being explicit avoids

build/config/android/internal_rules.gni

@@ -10,6 +10,7 @@ import("//build/config/coverage/coverage.gni")
 import("//build/config/dcheck_always_on.gni")
 import("//build/config/python.gni")
 import("//build/config/sanitizers/sanitizers.gni")
+import("//build/toolchain/goma.gni")
 import("//build/util/generate_wrapper.gni")
 import("//build_overrides/build.gni")
 assert(is_android)
@@ -2729,6 +2730,9 @@ if (enable_java_templates) {
         "--processorpath=@FileArg($_rebased_build_config:javac:processor_classpath)",
         "--processors=@FileArg($_rebased_build_config:javac:processor_classes)",
       ]
+      if (use_java_goma) {
+        args += [ "--gomacc-path=$goma_dir/gomacc" ]
+      }
       if (defined(invoker.srcjar_filearg)) {
         args += [ "--java-srcjars=${invoker.srcjar_filearg}" ]
       }

build/toolchain/goma.gni

@@ -29,6 +29,9 @@ declare_args() {
 }
 
 declare_args() {
+  # TODO(crbug.com/726475): true if use_goma = true in the future.
+  use_java_goma = false
+
   # Auto-configure for Goma RBE backend.
   # TODO(crbug.com/1015730): true if use_goma = true in the future.
   ios_use_goma_rbe = false