Add ES3 commands GetVertexAttribI{u}iv to GPU command buffer.

gpu/command_buffer/client/vertex_array_object_manager.cc

Index: gpu/command_buffer/client/vertex_array_object_manager.cc
diff --git a/gpu/command_buffer/client/vertex_array_object_manager.cc b/gpu/command_buffer/client/vertex_array_object_manager.cc
index a1098e960f2544fd6e99356caf010ef8d3322848..8b0385d7cbb430346a78213e9660870bfd9b0712 100644
--- a/gpu/command_buffer/client/vertex_array_object_manager.cc
+++ b/gpu/command_buffer/client/vertex_array_object_manager.cc
@@ -282,9 +282,11 @@ bool VertexArrayObject::GetVertexAttrib(
     case GL_VERTEX_ATTRIB_ARRAY_NORMALIZED:
       *param = attrib->normalized();
       break;
+    case GL_VERTEX_ATTRIB_ARRAY_INTEGER:
+      // TODO(zmo): cache this on the client side.
+      return false;
     default:
       return false;  // pass through to service side.
-      break;
   }
   return true;
 }