Refactor DocumentLoader to avoid SharedBuffer::Data()

Use a segment iterator insted.

BUG=728627

Change-Id: I6bb88a0696e920f2751181d4c8acc9d790787e26
Reviewed-on: https://chromium-review.googlesource.com/577672Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Hajime Hoshi <hajimehoshi@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>
Cr-Commit-Position: refs/heads/master@{#488200}

third_party/WebKit/Source/core/loader/DocumentLoader.cpp

@@ -816,7 +816,12 @@ bool DocumentLoader::MaybeCreateArchive() {
       kSandboxAll &
       ~(kSandboxPopups | kSandboxPropagatesToAuxiliaryBrowsingContexts));
 
-  CommitData(main_resource->Data()->Data(), main_resource->Data()->size());
+  RefPtr<SharedBuffer> data(main_resource->Data());
+  data->ForEachSegment(
+      [this](const char* segment, size_t segment_size, size_t segment_offset) {
+        CommitData(segment, segment_size);
+        return true;
+      });
   return true;
 }