Add support for shared library resources to java_apk build rules.

build/java_apk.gypi

Index: build/java_apk.gypi
diff --git a/build/java_apk.gypi b/build/java_apk.gypi
index 18e6ccfe7b85b2c3c48ebd30c0cf4220f008c961..7a67fe2de264cf5aecc16942219b16f1d78b2147 100644
--- a/build/java_apk.gypi
+++ b/build/java_apk.gypi
@@ -44,6 +44,9 @@
 #    shared library to be included in this apk. A stripped copy of the
 #    library will be included in the apk.
 #  resource_dir - The directory for resources.
+#  shared_resources - Generate resources and R.java classes compatible with the
+#    shared library resources mechanism. This is primarily intended to be used
+#    by the system WebView build.
 #  R_package - A custom Java package to generate the resource file R.java in.
 #    By default, the package given in AndroidManifest.xml will be used.
 #  use_chromium_linker - Enable the content dynamic linker that allows sharing the
@@ -126,6 +129,7 @@
     'resource_zip_path': '<(intermediate_dir)/<(_target_name).resources.zip',
     'resource_packaged_apk_name': '<(apk_name)-resources.ap_',
     'resource_packaged_apk_path': '<(intermediate_dir)/<(resource_packaged_apk_name)',
+    'shared_resources%': 0,
     'unsigned_apk_path': '<(intermediate_dir)/<(apk_name)-unsigned.apk',
     'final_apk_path%': '<(PRODUCT_DIR)/apks/<(apk_name).apk',
     'incomplete_apk_path': '<(intermediate_dir)/<(apk_name)-incomplete.apk',
@@ -575,7 +579,10 @@
             'additional_res_packages=': [],
           }],
           ['res_v14_verify_only == 1', {
-            'process_resources_options': ['--v14-verify-only']
+            'process_resources_options+': ['--v14-verify-only']
+          }],
+          ['shared_resources == 1', {
+            'process_resources_options+': ['--shared-resources']
           }],
         ],
       },