Revert of Allow BlobDataHandles to be copied, and have their UUIDs read, on any threa...

Revert of Allow BlobDataHandles to be copied, and have their UUIDs read, on any thread. (https://codereview.chromium.org/259773006/)

Reason for revert:
I'm sorry to revert this change. It looks like it breaks the ASAN bot:

http://build.chromium.org/p/chromium.memory/builders/Linux%20ASan%20LSan%20Tests%20%282%29/builds/2161/steps/content_unittests/logs/ResolveBlobAndCreateUploadDataStream

Direct leak of 120 byte(s) in 3 object(s) allocated from:
    #0 0x520dbb in operator new(unsigned long) /usr/local/google/work/chromium/src/third_party/llvm/projects/compiler-rt/lib/asan/asan_new_delete.cc:62
    #1 0x3a0f611 in webkit_blob::BlobDataHandle::BlobDataHandle(webkit_blob::BlobData*, webkit_blob::BlobStorageContext*, base::SequencedTaskRunner*) webkit/browser/blob/blob_data_handle.cc:42
    #2 0x3a0fd71 in webkit_blob::BlobStorageContext::GetBlobDataFromUUID(std::string const&) webkit/browser/blob/blob_storage_context.cc:69
    #3 0x268955d in ResolveBlobReference content/browser/loader/upload_data_stream_builder.cc:73
...

Original issue's description:
> Allow BlobDataHandles to be copied, and have their UUIDs read, on any thread.
>
> BUG=108012
>
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=266817
>
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=267423

TBR=michaeln@chromium.org,piman@chromium.org,ericu@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=108012

Review URL: https://codereview.chromium.org/261683005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@267479 0039d316-1c4b-4281-b951-d872f2087c98