The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9fc9575ca4928dcca5d6ca5b8c36ffe87466ab46

commit 9fc9575ca4928dcca5d6ca5b8c36ffe87466ab46
Author: nhiroki <nhiroki@chromium.org>
Date: Tue Apr 19 04:43:03 2016

ServiceWorker: Remove unused MessageEvent implementation from ServiceWorkerGlobalScope

This is a follow-up patch for  issue 598608 . After ExtendableMessageEvent is
shipped, MessageEvent on ServiceWorkerGlobalScope is no longer used. This patch
removes implementation and UMA for the event and adds a new UMA for
ExtendableMessageEvent instead.

BUG= 570820 ,  602924 

Review URL: https://codereview.chromium.org/1877283002

Cr-Commit-Position: refs/heads/master@{#388136}

[modify] https://crrev.com/9fc9575ca4928dcca5d6ca5b8c36ffe87466ab46/content/browser/service_worker/service_worker_dispatcher_host.cc
[modify] https://crrev.com/9fc9575ca4928dcca5d6ca5b8c36ffe87466ab46/content/browser/service_worker/service_worker_dispatcher_host.h
[modify] https://crrev.com/9fc9575ca4928dcca5d6ca5b8c36ffe87466ab46/content/browser/service_worker/service_worker_metrics.cc
[modify] https://crrev.com/9fc9575ca4928dcca5d6ca5b8c36ffe87466ab46/content/browser/service_worker/service_worker_version.cc
[modify] https://crrev.com/9fc9575ca4928dcca5d6ca5b8c36ffe87466ab46/content/browser/service_worker/service_worker_version.h
[modify] https://crrev.com/9fc9575ca4928dcca5d6ca5b8c36ffe87466ab46/content/browser/service_worker/service_worker_version_unittest.cc
[modify] https://crrev.com/9fc9575ca4928dcca5d6ca5b8c36ffe87466ab46/content/child/service_worker/web_service_worker_impl.cc
[modify] https://crrev.com/9fc9575ca4928dcca5d6ca5b8c36ffe87466ab46/content/common/service_worker/service_worker_messages.h
[modify] https://crrev.com/9fc9575ca4928dcca5d6ca5b8c36ffe87466ab46/content/renderer/service_worker/service_worker_context_client.cc
[modify] https://crrev.com/9fc9575ca4928dcca5d6ca5b8c36ffe87466ab46/content/renderer/service_worker/service_worker_context_client.h
[modify] https://crrev.com/9fc9575ca4928dcca5d6ca5b8c36ffe87466ab46/third_party/WebKit/Source/modules/serviceworkers/ExtendableMessageEvent.idl
[modify] https://crrev.com/9fc9575ca4928dcca5d6ca5b8c36ffe87466ab46/third_party/WebKit/Source/modules/serviceworkers/ExtendableMessageEventInit.idl
[modify] https://crrev.com/9fc9575ca4928dcca5d6ca5b8c36ffe87466ab46/third_party/WebKit/Source/platform/RuntimeEnabledFeatures.in
[modify] https://crrev.com/9fc9575ca4928dcca5d6ca5b8c36ffe87466ab46/third_party/WebKit/Source/web/ServiceWorkerGlobalScopeProxy.cpp
[modify] https://crrev.com/9fc9575ca4928dcca5d6ca5b8c36ffe87466ab46/third_party/WebKit/Source/web/ServiceWorkerGlobalScopeProxy.h
[modify] https://crrev.com/9fc9575ca4928dcca5d6ca5b8c36ffe87466ab46/third_party/WebKit/Source/web/WebRuntimeFeatures.cpp
[modify] https://crrev.com/9fc9575ca4928dcca5d6ca5b8c36ffe87466ab46/third_party/WebKit/public/web/WebRuntimeFeatures.h
[modify] https://crrev.com/9fc9575ca4928dcca5d6ca5b8c36ffe87466ab46/third_party/WebKit/public/web/modules/serviceworker/WebServiceWorkerContextProxy.h
[modify] https://crrev.com/9fc9575ca4928dcca5d6ca5b8c36ffe87466ab46/tools/metrics/histograms/histograms.xml