Update from https://crrev.com/304715

net/url_request/sdch_dictionary_fetcher.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/url_request/sdch_dictionary_fetcher.h"
 
 #include <stdint.h>
 
 #include "base/auto_reset.h"
 #include "base/bind.h"
 #include "base/compiler_specific.h"
+#include "base/profiler/scoped_tracker.h"
 #include "base/thread_task_runner_handle.h"
 #include "net/base/load_flags.h"
 #include "net/base/sdch_net_log_params.h"
 #include "net/url_request/url_request_context.h"
 #include "net/url_request/url_request_status.h"
 #include "net/url_request/url_request_throttler_manager.h"
 
 namespace {
 
 const int kBufferSize = 4096;
@@ skipping 52 matching lines @@
   while (!fetch_queue_.empty())
     fetch_queue_.pop();
   attempted_load_.clear();
   weak_factory_.InvalidateWeakPtrs();
   current_request_.reset(NULL);
   buffer_ = NULL;
   dictionary_.clear();
 }
 
 void SdchDictionaryFetcher::OnResponseStarted(URLRequest* request) {
+  // TODO(vadimt): Remove ScopedTracker below once crbug.com/423948 is fixed.
+  tracked_objects::ScopedTracker tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "423948 SdchDictionaryFetcher::OnResponseStarted"));
+
   DCHECK(CalledOnValidThread());
   DCHECK_EQ(request, current_request_.get());
   DCHECK_EQ(next_state_, STATE_REQUEST_STARTED);
 
   // The response has started, so the stream can be read from.
   next_state_ = STATE_REQUEST_READING;
 
   // If this function was synchronously called, the containing
   // state machine loop will handle the state transition. Otherwise,
   // restart the state machine loop.
   if (in_loop_)
     return;
 
   DoLoop(request->status().error());
 }
 
 void SdchDictionaryFetcher::OnReadCompleted(URLRequest* request,
                                             int bytes_read) {
+  // TODO(vadimt): Remove ScopedTracker below once crbug.com/423948 is fixed.
+  tracked_objects::ScopedTracker tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "423948 SdchDictionaryFetcher::OnReadCompleted"));
+
   DCHECK(CalledOnValidThread());
   DCHECK_EQ(request, current_request_.get());
   DCHECK_EQ(next_state_, STATE_REQUEST_READING);
 
   // No state transition is required in this function; the
   // completion of the request is detected in DoRead().
 
   if (request->status().is_success())
     dictionary_.append(buffer_->data(), bytes_read);
 
@@ skipping 80 matching lines @@
   if (rv != OK) {
     current_request_.reset();
     buffer_ = NULL;
     next_state_ = STATE_IDLE;
 
     return OK;
   }
 
   next_state_ = STATE_REQUEST_READING;
   int bytes_read = 0;
-  if (!current_request_->Read(buffer_.get(), kBufferSize, &bytes_read)) {
-    if (current_request_->status().is_io_pending())
-      return ERR_IO_PENDING;
+  current_request_->Read(buffer_.get(), kBufferSize, &bytes_read);
+  if (current_request_->status().is_io_pending())
+    return ERR_IO_PENDING;
 
-    if (current_request_->status().error() == OK) {
-      // This "should never happen", but if it does the result will be
-      // an infinite loop.  It's not clear how to handle a read failure
-      // without a promise to invoke the callback at some point in the future,
-      // so the request is failed.
-      SdchManager::SdchErrorRecovery(SDCH_DICTIONARY_FETCH_READ_FAILED);
-      current_request_->net_log().AddEvent(
-          NetLog::TYPE_SDCH_DICTIONARY_ERROR,
-          base::Bind(&NetLogSdchDictionaryFetchProblemCallback,
-                     SDCH_DICTIONARY_FETCH_READ_FAILED, current_request_->url(),
-                     true));
-      DLOG(FATAL)
-          << "URLRequest::Read() returned false without IO pending or error!";
-      return ERR_FAILED;
-    }
+  if (bytes_read < 0 || !current_request_->status().is_success()) {
+    if (current_request_->status().error() != OK)
+      return current_request_->status().error();
 
-    return current_request_->status().error();
+    // An error with request status of OK should not happen,
+    // but there's enough machinery underneath URLRequest::Read()
+    // that this routine checks for that case.
+    net::Error error =
+        current_request_->status().status() == URLRequestStatus::CANCELED ?
+        ERR_ABORTED : ERR_FAILED;
+    current_request_->net_log().AddEventWithNetErrorCode(
+        NetLog::TYPE_SDCH_DICTIONARY_FETCH_IMPLIED_ERROR, error);
+    return error;
   }
 
-  if (bytes_read != 0)
+  if (bytes_read == 0)
+    next_state_ = STATE_REQUEST_COMPLETE;
+  else
     dictionary_.append(buffer_->data(), bytes_read);
-  else
-    next_state_ = STATE_REQUEST_COMPLETE;
 
   return OK;
 }
 
 int SdchDictionaryFetcher::DoCompleteRequest(int rv) {
   DCHECK(CalledOnValidThread());
 
   // If the dictionary was successfully fetched, add it to the manager.
   if (rv == OK) {
     dictionary_fetched_callback_.Run(dictionary_, current_request_->url(),
                                      current_request_->net_log());
   }
 
   current_request_.reset();
   buffer_ = NULL;
   dictionary_.clear();
 
   next_state_ = STATE_IDLE;
 
   return OK;
 }
 
 }  // namespace net