Add test jar generation logic for ant builds.

build/all_android.gyp

Index: build/all_android.gyp
diff --git a/build/all_android.gyp b/build/all_android.gyp
index c4ade0708230590a24962ab85b43855244b0441e..3d215ab946a8c1b11ee4877f83ed3b7c1ef172b8 100644
--- a/build/all_android.gyp
+++ b/build/all_android.gyp
@@ -115,5 +115,35 @@
         '../content/content.gyp:content_browsertests',
       ],
     },
+    {
+      # Target for creating common output build directories. Creating output
+      # dirs beforehand ensures that build scripts can assume these folders to
+      # exist and there are no race conditions resulting from build scripts
+      # trying to create these directories.
+      # The build/java.gypi target depends on this target.
+      'target_name': 'build_output_dirs',
+      'type': 'none',
+      'actions': [
+        {
+          'action_name': 'create_java_output_dirs',
+          'variables' : {
+          'output_dirs' : [
+            '<(PRODUCT_DIR)/apks',
+            '<(PRODUCT_DIR)/lib.java',
+            '<(PRODUCT_DIR)/test.lib.java',
+           ]
+          },
+          'inputs' : [],
+          'outputs': [
+            '<@(output_dirs)'
+          ],
+          'action': [
+            'mkdir',
+            '-p',
+            '<@(output_dirs)',
+          ],
+        },
+      ],
+    }, # build_output_dirs
   ],  # targets
 }