Revert "Copy some more BlobReader state to the stack and alias it."

This reverts commit e67557cd.

Reason for revert: Issue 864351 has been traced to a bug in ThirdPartyModulesBlocking.

Original change's description:
> Copy some more BlobReader state to the stack and alias it.
> 
> Temporarily add some values to minidumps, to help diagnose BlobReader
> crash reports.
> 
> Bug: 864351
> Change-Id: I048600d890496247fc966442d8f533d4b9eb51c8
> Reviewed-on: https://chromium-review.googlesource.com/1196041
> Reviewed-by: Marijn Kruisselbrink <mek@chromium.org>
> Commit-Queue: Wez <wez@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#587476}

TBR=wez@chromium.org,mek@chromium.org,brucedawson@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 864351
Change-Id: Ibb9809ce230a615ec18a36708d45635fc40ca8c1
Reviewed-on: https://chromium-review.googlesource.com/1216711Reviewed-by: Wez <wez@chromium.org>
Commit-Queue: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#589981}

storage/browser/blob/blob_reader.cc

@@ -226,14 +226,6 @@ BlobReader::Status BlobReader::Read(net::IOBuffer* buffer,
   if (net_error_ != net::OK)
     return Status::NET_ERROR;
 
-  // TODO(https://crbug.com/864351): Temporary diagnostics.
-  base::debug::Alias(&buffer);
-  base::debug::Alias(&dest_size);
-  uint64_t remaining_bytes = remaining_bytes_;
-  base::debug::Alias(&remaining_bytes);
-  const char* buffer_data = buffer->data();
-  base::debug::Alias(&buffer_data);
-
   DCHECK_GE(dest_size, 0ul);
   if (remaining_bytes_ < static_cast<uint64_t>(dest_size))
     dest_size = static_cast<int>(remaining_bytes_);
@@ -469,10 +461,6 @@ BlobReader::Status BlobReader::ReadLoop(int* bytes_read) {
 BlobReader::Status BlobReader::ReadItem() {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
 
-  // TODO(https://crbug.com/864351): Temporary diagnostics.
-  uint64_t remaining_bytes = remaining_bytes_;
-  base::debug::Alias(&remaining_bytes);
-
   // Are we done with reading all the blob data?
   if (remaining_bytes_ == 0)
     return Status::DONE;
@@ -496,8 +484,6 @@ BlobReader::Status BlobReader::ReadItem() {
   const BlobDataItem& item = *items.at(current_item_index_);
 
   // TODO(https://crbug.com/864351): Temporary diagnostics.
-  const BlobDataItem* item_ptr = &item;
-  base::debug::Alias(&item_ptr);
   uint64_t item_offset = item.offset();
   base::debug::Alias(&item_offset);
   uint64_t item_length = item.length();
@@ -510,12 +496,6 @@ BlobReader::Status BlobReader::ReadItem() {
     // TODO(https://crbug.com/864351): Temporary diagnostics.
     const char* item_bytes = item.bytes().data();
     base::debug::Alias(&item_bytes);
-    const char* read_buf_bytes = read_buf_->data();
-    base::debug::Alias(&read_buf_bytes);
-    int read_buf_size = read_buf_->size();
-    base::debug::Alias(&read_buf_size);
-    int read_buf_remaining = read_buf_->BytesRemaining();
-    base::debug::Alias(&read_buf_remaining);
 
     ReadBytesItem(item, bytes_to_read);
     return Status::DONE;