Revert "Make sure kFile BlobDataItems have a expected_modification_ti…

…me."

This reverts commit 9b568e6.

Reason for revert: this breaks XHR downloading to blobs, since the file that writes to might not be closed/updated until after the blob is created.

Original change's description:
> Make sure kFile BlobDataItems have a expected_modification_time.
> 
> Having expected_modification_time set guards us against files changing
> out from under us, and accidentally exposing those changes to the web.
> Without this change any files selected in <input> elements would be
> perpetually readable with whatever the file on disk changed to.
> 
> Bug: 710190
> Change-Id: I4b05ccfbe2d3c42116769d442bcec853973ff67c
> Reviewed-on: https://chromium-review.googlesource.com/920783
> Commit-Queue: Daniel Murphy <dmurph@chromium.org>
> Reviewed-by: Daniel Murphy <dmurph@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#538331}

TBR=dmurph@chromium.org,mek@chromium.org

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

Bug: 710190, 826178
Change-Id: I7f742f6d63d39a546c441203e5815abf5d0ba4b2
Reviewed-on: https://chromium-review.googlesource.com/981502
Commit-Queue: Marijn Kruisselbrink <mek@chromium.org>
Reviewed-by: Marijn Kruisselbrink <mek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#546278}

storage/browser/blob/blob_data_item.cc

@@ -167,16 +167,6 @@ void BlobDataItem::GrowFile(uint64_t new_length) {
   length_ = new_length;
 }
 
-// static
-void BlobDataItem::SetFileModificationTimes(
-    std::vector<scoped_refptr<BlobDataItem>> items,
-    std::vector<base::Time> times) {
-  DCHECK_EQ(items.size(), times.size());
-  for (size_t i = 0; i < items.size(); ++i) {
-    items[i]->expected_modification_time_ = times[i];
-  }
-}
-
 void PrintTo(const BlobDataItem& x, ::std::ostream* os) {
   const uint64_t kMaxDataPrintLength = 40;
   DCHECK(os);

storage/browser/blob/blob_data_item.h

@@ -167,10 +167,6 @@ class STORAGE_EXPORT BlobDataItem : public base::RefCounted<BlobDataItem> {
     expected_modification_time_ = time;
   }
 
-  static void SetFileModificationTimes(
-      std::vector<scoped_refptr<BlobDataItem>> items,
-      std::vector<base::Time> times);
-
   Type type_;
   uint64_t offset_;
   uint64_t length_;

storage/browser/blob/blob_storage_context.cc

@@ -14,7 +14,6 @@
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/callback_helpers.h"
-#include "base/files/file_util.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
@@ -24,7 +23,6 @@
 #include "base/numerics/safe_math.h"
 #include "base/strings/stringprintf.h"
 #include "base/task_runner.h"
-#include "base/task_scheduler/post_task.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/trace_event/memory_dump_manager.h"
 #include "base/trace_event/trace_event.h"
@@ -38,21 +36,6 @@ namespace storage {
 namespace {
 using ItemCopyEntry = BlobEntry::ItemCopyEntry;
 using QuotaAllocationTask = BlobMemoryController::QuotaAllocationTask;
-
-std::vector<base::Time> GetModificationTimes(
-    std::vector<base::FilePath> paths) {
-  std::vector<base::Time> result;
-  result.reserve(paths.size());
-  for (const auto& path : paths) {
-    base::File::Info info;
-    if (!base::GetFileInfo(path, &info)) {
-      result.emplace_back();
-      continue;
-    }
-    result.emplace_back(info.last_modified);
-  }
-  return result;
-}
 }  // namespace
 
 BlobStorageContext::BlobStorageContext()
@@ -245,29 +228,6 @@ std::unique_ptr<BlobDataHandle> BlobStorageContext::BuildBlobInternal(
   UMA_HISTOGRAM_COUNTS_1M("Storage.Blob.TotalUnsharedSize",
                           total_memory_needed / 1024);
 
-  std::vector<scoped_refptr<BlobDataItem>> items_needing_timestamp;
-  std::vector<base::FilePath> file_paths_needing_timestamp;
-  for (auto& item : entry->items_) {
-    if (item->item()->type() == BlobDataItem::Type::kFile &&
-        !item->item()->IsFutureFileItem() &&
-        item->item()->expected_modification_time().is_null()) {
-      items_needing_timestamp.push_back(item->item());
-      file_paths_needing_timestamp.push_back(item->item()->path());
-    }
-  }
-  if (!items_needing_timestamp.empty()) {
-    // Blob construction isn't blocked on getting these timestamps. The created
-    // blob will be fully functional whether or not timestamps are set. When
-    // the timestamp isn't set the blob just won't be able to detect the file
-    // on disk changing after the blob is created.
-    base::PostTaskWithTraitsAndReplyWithResult(
-        FROM_HERE, {base::MayBlock()},
-        base::BindOnce(&GetModificationTimes,
-                       std::move(file_paths_needing_timestamp)),
-        base::BindOnce(&BlobDataItem::SetFileModificationTimes,
-                       std::move(items_needing_timestamp)));
-  }
-
   size_t num_building_dependent_blobs = 0;
   std::vector<std::unique_ptr<BlobDataHandle>> dependent_blobs;
   // We hold a handle to all blobs we're using. This is important, as our memory

third_party/WebKit/LayoutTests/fast/filesystem/resources/file-writer-sync-write-overlapped.js

@@ -29,8 +29,9 @@ writer.write(blob);
 // Verify the contents.
 assert(writer.length == 2 * testData.length + extensionOffset);
 assert(writer.position == writer.length);
+var file = entry.file();
 var reader = new FileReaderSync();
-var contents = reader.readAsBinaryString(entry.file());
+var contents = reader.readAsBinaryString(file);
 var i;
 for (i = 0; i < testData.length + extensionOffset; ++i)
     assert(contents.charCodeAt(i) == testData.charCodeAt(i));
@@ -55,7 +56,7 @@ assert(writer.length == testData.length + extensionOffset);
 assert(writer.position == writer.length);
 
 // Verify the contents.
-contents = reader.readAsBinaryString(entry.file());
+contents = reader.readAsBinaryString(file);
 for (i = 0; i < extensionOffset; ++i)
     assert(contents.charCodeAt(i) == testData.charCodeAt(i));
 for (j = 0; i < writer.length; ++i, ++j)
@@ -79,7 +80,7 @@ assert(writer.length == 2 * testData.length);
 assert(writer.position == testData.length + extensionOffset);
 
 // Verify the contents.
-contents = reader.readAsBinaryString(entry.file());
+contents = reader.readAsBinaryString(file);
 for (i = 0; i < extensionOffset; ++i)
     assert(contents.charCodeAt(i) == testData.charCodeAt(i));
 for (j = 0; i < testData.length + extensionOffset; ++i, ++j)