aura: Attach lost context callback to the shared main thread context

content/content_tests.gypi

Index: content/content_tests.gypi
diff --git a/content/content_tests.gypi b/content/content_tests.gypi
index f3c3daff0d8867fad2785b6b228fdfbc3a35441c..a60f28414b4670da68b14c885e8f654d10335e74 100644
--- a/content/content_tests.gypi
+++ b/content/content_tests.gypi
@@ -859,6 +859,7 @@
             'browser/accessibility/accessibility_win_browsertest.cc',
             'browser/accessibility/cross_platform_accessibility_browsertest.cc',
             'browser/accessibility/dump_accessibility_tree_browsertest.cc',
+            'browser/aura/image_transport_factory_browsertest.cc',
             'browser/bookmarklet_browsertest.cc',
             'browser/browser_plugin/browser_plugin_host_browsertest.cc',
             'browser/browser_plugin/test_browser_plugin_embedder.cc',
@@ -1030,6 +1031,10 @@
                 'browser/plugin_browsertest.cc',
                 'browser/renderer_host/render_widget_host_view_win_browsertest.cc',
               ],
+            }, {
+              'sources/': [
+                ['exclude', '^browser/aura/'],
+              ],
             }],
             ['OS!="android" and OS!="ios"', {
               # npapi test plugin doesn't build on android or ios