Skip Service workers in requests for mime handler plugins

BUG=808838
TEST=./browser_tests --gtest_filter=*/ServiceWorkerTest.MimeHandlerView*

Cq-Include-Trybots: master.tryserver.chromium.linux:linux_mojo
Change-Id: I82e75c200091babbab648a04232db47e2938d914
Reviewed-on: https://chromium-review.googlesource.com/914150
Commit-Queue: Rob Wu <rob@robwu.nl>
Reviewed-by: Istiaque Ahmed <lazyboy@chromium.org>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537386}
void MimeHandlerViewContainer::DidReceiveData(const char* data,
                                              int data_length) {
  view_id_ += std::string(data, data_length);
}

void MimeHandlerViewContainer::DidReceiveData(const char* data,
                                              int data_length) {
  view_id_ += std::string(data, data_length);
}
