URLRequestJob: change ReadRawData contract

Previously, the interface for URLRequestJob::ReadRawData was as follows:

  bool ReadRawData(IOBuffer*, int, int*)

Subclasses were expected to signal completion of the ReadRawData call by
calling NotifyDone, SetStatus, or maybe one of the other Notify* functions
on URLRequestJob, most of which do internal housekeeping and also drive the
URLRequest's state machine. This made it difficult to reason about the
URLRequestJob's state machine and needlessly complicated most of URLRequestJob.

The new interface is as follows:

  int ReadRawData(IOBuffer*, int)

Subclasses are required to either:

a) Return ERR_IO_PENDING, and call ReadRawDataComplete when the read completes in any way, or
b) Return a count of bytes read >= 0, indicating synchronous success, or
c) Return another error code < 0, indicating synchronous failure.

This substantially narrows the interface between URLRequestJob and its
subclasses and moves the logic for the URLRequest state machine largely into
URLRequestJob.

Also, the signature of URLRequestJob::ReadFilteredData and some other internal
URLRequestJob helpers changes to propagate detailed error codes instead of
coercing all errors to FAILED.

TBR=michaeln@chromium.org,mnaganov@chromium.org,skyostil@chromium.org,eugenebut@chromium.org,davidben@chromium.org,falken@chromium.org,mtomasz@chromium.org, sky@chromium.org,jianli@chromium.org,zork@chromium.org,rdsmith@chromium.org
BUG=553300

Review URL: https://codereview.chromium.org/1467603002

Cr-Commit-Position: refs/heads/master@{#361158}

1 files changed, 1 insertions, 1 deletions

diff --git a/net/url_request/url_request_test_job.h b/net/url_request/url_request_test_job.h
index 09b31a4..eb1db01 100644
--- a/net/url_request/url_request_test_job.h
+++ b/net/url_request/url_request_test_job.h
@@ -111,7 +111,7 @@ class NET_EXPORT_PRIVATE URLRequestTestJob : public URLRequestJob {
   // Job functions
   void SetPriority(RequestPriority priority) override;
   void Start() override;
-  bool ReadRawData(IOBuffer* buf, int buf_size, int* bytes_read) override;
+  int ReadRawData(IOBuffer* buf, int buf_size) override;
   void Kill() override;
   bool GetMimeType(std::string* mime_type) const override;
   void GetResponseInfo(HttpResponseInfo* info) override;