Remove redundant reading and writing of data about SharedBuffer.

third_party/WebKit/Source/platform/BUILD.gn

Index: third_party/WebKit/Source/platform/BUILD.gn
diff --git a/third_party/WebKit/Source/platform/BUILD.gn b/third_party/WebKit/Source/platform/BUILD.gn
index 444d9bfac295cbf71befdfc61cb7e3cc6d997179..ec0d46a3a40a8d6faaf96f2a7c83d828d8079657 100644
--- a/third_party/WebKit/Source/platform/BUILD.gn
+++ b/third_party/WebKit/Source/platform/BUILD.gn
@@ -316,6 +316,8 @@ component("platform") {
     "SharedBuffer.h",
     "SharedBufferChunkReader.cpp",
     "SharedBufferChunkReader.h",
+    "SharedBufferStep.cpp",
+    "SharedBufferStep.h",
     "StorageQuotaCallbacks.h",
     "Supplementable.cpp",
     "Supplementable.h",
@@ -2046,6 +2048,28 @@ test("image_decode_bench") {
   defines = [ "INSIDE_BLINK" ]
 }
 
+test("deferred_image_decode_bench") {
+  visibility = []  # Allow re-assignment of list.
+  visibility = [ "*" ]
+
+  sources = [
+    "testing/DeferredImageDecodeBench.cpp",
+  ]
+
+  deps = [
+    ":platform",
+    "//third_party/WebKit/Source/platform/wtf",
+    "//ui/gfx:test_support",
+  ]
+
+  configs += [
+    "//third_party/WebKit/Source/platform/wtf:wtf_config",
+    "//third_party/WebKit/Source:config",
+  ]
+
+  defines = [ "INSIDE_BLINK" ]
+}
+
 test("blink_platform_perftests") {
   sources = [
     "scheduler/base/task_queue_manager_delegate_for_test.cc",