Move stash_backend into extensions/browser/mojo.

extensions/extensions.gyp

Index: extensions/extensions.gyp
diff --git a/extensions/extensions.gyp b/extensions/extensions.gyp
index dca4307954adf02777834227502105ca11dbc4e4..9c3d7a2f892947eaa4fc303203a39f3f876456bd 100644
--- a/extensions/extensions.gyp
+++ b/extensions/extensions.gyp
@@ -19,7 +19,7 @@
       ],
       'sources': [
         'common/mojo/keep_alive.mojom',
-        'common/stash.mojom',
+        'common/mojo/stash.mojom',
       ],
     },
     {
@@ -709,6 +709,8 @@
         'browser/management_policy.h',
         'browser/mojo/keep_alive_impl.cc',
         'browser/mojo/keep_alive_impl.h',
+        'browser/mojo/stash_backend.cc',
+        'browser/mojo/stash_backend.h',
         'browser/notification_types.h',
         'browser/null_app_sorting.cc',
         'browser/null_app_sorting.h',
@@ -731,8 +733,6 @@
         'browser/script_execution_observer.h',
         'browser/script_executor.cc',
         'browser/script_executor.h',
-        'browser/stash_backend.cc',
-        'browser/stash_backend.h',
         'browser/state_store.cc',
         'browser/state_store.h',
         'browser/suggest_permission_util.cc',
@@ -1163,11 +1163,11 @@
         'browser/lazy_background_task_queue_unittest.cc',
         'browser/management_policy_unittest.cc',
         'browser/mojo/keep_alive_impl_unittest.cc',
+        'browser/mojo/stash_backend_unittest.cc',
         'browser/process_manager_unittest.cc',
         'browser/process_map_unittest.cc',
         'browser/quota_service_unittest.cc',
         'browser/runtime_data_unittest.cc',
-        'browser/stash_backend_unittest.cc',
         'browser/value_store/leveldb_value_store_unittest.cc',
         'browser/value_store/testing_value_store_unittest.cc',
         'browser/value_store/value_store_change_unittest.cc',