[BlobAsync] Adding better error reporting and some new tests.

storage/browser/blob/blob_data_handle.cc

Index: storage/browser/blob/blob_data_handle.cc
diff --git a/storage/browser/blob/blob_data_handle.cc b/storage/browser/blob/blob_data_handle.cc
index 4778f3914a1d8736403b1e716b5c8a70293dc817..748142e3dfb06035ed80a88386bdce557d1b6e4f 100644
--- a/storage/browser/blob/blob_data_handle.cc
+++ b/storage/browser/blob/blob_data_handle.cc
@@ -72,15 +72,6 @@ BlobDataHandle::BlobDataHandleShared::BlobDataHandleShared(
   context_->IncrementBlobRefCount(uuid);
 }
 
-void BlobDataHandle::BlobDataHandleShared::RunOnConstructionComplete(
-    const base::Callback<void(bool)>& done) {
-  if (!context_.get()) {
-    done.Run(false);
-    return;
-  }
-  context_->RunOnConstructionComplete(uuid_, done);
-}
-
 scoped_ptr<BlobReader> BlobDataHandle::CreateReader(
     FileSystemContext* file_system_context,
     base::SequencedTaskRunner* file_task_runner) const {
@@ -90,13 +81,6 @@ scoped_ptr<BlobReader> BlobDataHandle::CreateReader(
       file_task_runner));
 }
 
-scoped_ptr<BlobDataSnapshot>
-BlobDataHandle::BlobDataHandleShared::CreateSnapshot() const {
-  if (!context_.get())
-    return nullptr;
-  return context_->CreateSnapshot(uuid_);
-}
-
 BlobDataHandle::BlobDataHandleShared::~BlobDataHandleShared() {
   if (context_.get())
     context_->DecrementBlobRefCount(uuid_);
@@ -145,14 +129,20 @@ bool BlobDataHandle::IsBroken() const {
 }
 
 void BlobDataHandle::RunOnConstructionComplete(
-    const base::Callback<void(bool)>& done) {
+    const BlobConstructedCallback& done) {
   DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
-  shared_->RunOnConstructionComplete(done);
+  if (!shared_->context_.get()) {
+    done.Run(false, IPCBlobCreationCancelCode::UNKNOWN);

[jsbell, 2016/04/04 20:41:19]

Add a code for this case?

[dmurph, 2016/04/04 22:17:42]

This is a crazy edge case, where the context is even around (so our system is
shutting down). I'm not sure if this warrants an enum value. Michael, WDYT?

+    return;
+  }
+  shared_->context_->RunOnConstructionComplete(shared_->uuid_, done);
 }
 
 scoped_ptr<BlobDataSnapshot> BlobDataHandle::CreateSnapshot() const {
   DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
-  return shared_->CreateSnapshot();
+  if (!shared_->context_.get())
+    return nullptr;
+  return shared_->context_->CreateSnapshot(shared_->uuid_);
 }
 
 const std::string& BlobDataHandle::uuid() const {