Add incremental_apk_by_default GN arg.

testing/test.gni

Index: testing/test.gni
diff --git a/testing/test.gni b/testing/test.gni
index b6677d45fc46d62ab61b6e78be6b66f5ddab9a5f..43ecd56c18e4f640526cbd353cdf2c1d8c16b9eb 100644
--- a/testing/test.gni
+++ b/testing/test.gni
@@ -176,13 +176,19 @@ template("test") {
 
     group(target_name) {
       testonly = true
-      deps = [
-        ":$_test_runner_target",
-      ]
-      if (_use_raw_android_executable) {
-        deps += [ ":$_dist_target" ]
+      if (incremental_apk_by_default && !_use_raw_android_executable) {
+        deps = [
+          ":${target_name}_incremental",
+        ]
       } else {
-        deps += [ ":$_apk_target" ]
+        deps = [
+          ":$_test_runner_target",
+        ]
+        if (_use_raw_android_executable) {
+          deps += [ ":$_dist_target" ]
+        } else {
+          deps += [ ":$_apk_target" ]
+        }
       }
     }