Deprecate FileReaderSync in service workers.

third_party/WebKit/Source/core/fileapi/FileReaderSync.cpp

Index: third_party/WebKit/Source/core/fileapi/FileReaderSync.cpp
diff --git a/third_party/WebKit/Source/core/fileapi/FileReaderSync.cpp b/third_party/WebKit/Source/core/fileapi/FileReaderSync.cpp
index 05dc1e43ef4be857448212d4450f97d2f0c3c0b1..100940f48f97aa991b09819cf7bf397ba0abe029 100644
--- a/third_party/WebKit/Source/core/fileapi/FileReaderSync.cpp
+++ b/third_party/WebKit/Source/core/fileapi/FileReaderSync.cpp
@@ -36,6 +36,7 @@
 #include "core/fileapi/Blob.h"
 #include "core/fileapi/FileError.h"
 #include "core/fileapi/FileReaderLoader.h"
+#include "core/frame/Deprecation.h"
 #include "platform/Histogram.h"
 
 namespace blink {
@@ -53,6 +54,11 @@ enum class WorkerType {
 }  // namespace
 
 FileReaderSync::FileReaderSync(ExecutionContext* context) {
+  if (context->isServiceWorkerGlobalScope()) {
+    Deprecation::countDeprecation(context,
+                                  UseCounter::FileReaderSyncInServiceWorker);
+  }
+
   WorkerType type = WorkerType::OTHER;
   if (context->isDedicatedWorkerGlobalScope())
     type = WorkerType::DEDICATED_WORKER;