Disable zoom bubble for PDF extension.

components/ui_zoom.gypi

Index: components/ui_zoom.gypi
diff --git a/components/ui_zoom.gypi b/components/ui_zoom.gypi
index ddab2cabb627c9e839b3763b40a69beafec60bfb..5048357f73354028ea2bf570e1f5346966557cdf 100644
--- a/components/ui_zoom.gypi
+++ b/components/ui_zoom.gypi
@@ -31,6 +31,23 @@
         'ui/zoom/zoom_event_manager_observer.h',
         'ui/zoom/zoom_observer.h'
       ],
+    },
+    {
+      'target_name': 'ui_zoom_test_utils',
+      'type': 'static_library',
+      'include_dirs': [
+        '..',
+      ],
+      'dependencies': [
+        '../base/base.gyp:base',
+        '../content/content.gyp:content_browser',
+        '../content/content.gyp:content_common',
+        '../components/components.gyp:ui_zoom',
+      ],
+      'sources': [
+        'ui/zoom/zoom_test_utils.cc',
+        'ui/zoom/zoom_test_utils.h'
+      ],
     }
   ],
 }