Fix JNI generation dependency in android_webview_unittests.

In the current gyp rules, the unittests depend on the following three
children: (1) java, (2) native and (3) jni generation. This is not
correct as (2) has a functional dependency on (2). Having (3) being a
sibling of (2), as it is now, introduces a race when building the
unittest target from clean.
This change fixes the problem making the jni generation step a
dependency of the native build, rather than a sibling.

BUG=None
TEST=ninja -C out/Debug android_webview_unittests_apk
NOTRY=true

Review URL: https://codereview.chromium.org/116043010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243426 0039d316-1c4b-4281-b951-d872f2087c98

android_webview/android_webview_tests.gypi

@@ -74,6 +74,7 @@
         '../testing/gtest.gyp:gtest',
         '../ui/ui.gyp:ui_base_jni_headers',
         'android_webview_common',
+        'android_webview_unittests_jni',
       ],
       'include_dirs': [
         '..',
@@ -119,7 +120,6 @@
       'dependencies': [
         'android_webview_unittest_java',
         'android_webview_unittests',
-        'android_webview_unittests_jni',
       ],
       'variables': {
         'test_suite_name': 'android_webview_unittests',