Relanding "Multiprocess test client: Android child process launcher rework."

testing/test.gni

Index: testing/test.gni
diff --git a/testing/test.gni b/testing/test.gni
index e4cce69a94ae97cd9ccfd101fbcb6a73437ff2aa..9aa7cc47de7e59b196425c13e21ea341b4dc3734 100644
--- a/testing/test.gni
+++ b/testing/test.gni
@@ -6,6 +6,12 @@
 # TEST SETUP
 # ==============================================================================
 
+if (is_android) {
+  import("//build/config/android/config.gni")
+  import("//build/config/android/rules.gni")
+  import("//build/config/sanitizers/sanitizers.gni")
+}
+
 # Define a test as an executable (or apk on Android) with the "testonly" flag
 # set.
 # Variable:
@@ -13,10 +19,6 @@
 #   use_native_activity: Test implements ANativeActivity_onCreate().
 template("test") {
   if (is_android) {
-    import("//build/config/android/config.gni")
-    import("//build/config/android/rules.gni")
-    import("//build/config/sanitizers/sanitizers.gni")
-
     _use_raw_android_executable = defined(invoker.use_raw_android_executable) &&
                                   invoker.use_raw_android_executable
 
@@ -118,6 +120,9 @@ template("test") {
           install_script_name = "install_${invoker.output_name}"
         }
 
+        # Add the Java classes so that each target does not have to do it.
+        deps += [ "//base/test:test_support_java" ]
+
         # TODO(agrieve): Remove this data_dep once bots don't build the _apk
         #     target (post-GYP).
         # It's a bit backwards for the apk to depend on the runner script, since