Revert of Fix a pair of ResourceLoader cancellation/error bugs.

content/browser/loader/resource_loader.cc

 // Copyright (c) 2012 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 "content/browser/loader/resource_loader.h"
 
 #include <utility>
 
 #include "base/callback_helpers.h"
 #include "base/command_line.h"
@@ skipping 332 matching lines @@
 
   DVLOG(1) << "OnResponseStarted: " << request_->url().spec();
 
   if (!request_->status().is_success()) {
     ResponseCompleted();
     return;
   }
 
   CompleteResponseStarted();
 
-  // If the handler deferred the request, it will resume the request later. If
-  // the request was cancelled, the request will call back into |this| with a
-  // bogus read completed error.
-  if (is_deferred() || !request_->status().is_success())
+  if (is_deferred())
     return;
 
-  StartReading(false);  // Read the first chunk.
+  if (request_->status().is_success())
+    StartReading(false);  // Read the first chunk.
+  else
+    ResponseCompleted();
 }
 
 void ResourceLoader::OnReadCompleted(net::URLRequest* unused, int bytes_read) {
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("loading"),
                "ResourceLoader::OnReadCompleted");
   DCHECK_EQ(request_.get(), unused);
   DVLOG(1) << "OnReadCompleted: \"" << request_->url().spec() << "\""
            << " bytes_read = " << bytes_read;
 
   // bytes_read == -1 always implies an error.
   if (bytes_read == -1 || !request_->status().is_success()) {
     ResponseCompleted();
     return;
   }
 
   CompleteRead(bytes_read);
 
   // If the handler cancelled or deferred the request, do not continue
-  // processing the read. If canceled, either the request will call into |this|
-  // with a bogus read error, or, if the request was completed, a task posted
-  // from ResourceLoader::CancelREquestInternal will run OnResponseCompleted.
+  // processing the read. If cancelled, the URLRequest has already been
+  // cancelled and will schedule an erroring OnReadCompleted later. If deferred,
+  // do nothing until resumed.
+  //
+  // Note: if bytes_read is 0 (EOF) and the handler defers, resumption will call
+  // ResponseCompleted().
   if (is_deferred() || !request_->status().is_success())
     return;
 
   if (bytes_read > 0) {
     StartReading(true);  // Read the next chunk.
   } else {
     // TODO(darin): Remove ScopedTracker below once crbug.com/475761 is fixed.
     tracked_objects::ScopedTracker tracking_profile(
         FROM_HERE_WITH_EXPLICIT_FUNCTION("475761 ResponseCompleted()"));
 
@@ skipping 161 matching lines @@
     read_deferral_start_time_ = base::TimeTicks::Now();
     deferred_stage_ = DEFERRED_READ;  // Read first chunk when resumed.
   }
 }
 
 void ResourceLoader::StartReading(bool is_continuation) {
   int bytes_read = 0;
   ReadMore(&bytes_read);
 
   // If IO is pending, wait for the URLRequest to call OnReadCompleted.
-  // On error or cancellation, wait for notification of failure.
-  if (request_->status().is_io_pending() || !request_->status().is_success())
+  if (request_->status().is_io_pending())
     return;
 
   if (!is_continuation || bytes_read <= 0) {
     OnReadCompleted(request_.get(), bytes_read);
   } else {
     // Else, trigger OnReadCompleted asynchronously to avoid starving the IO
     // thread in case the URLRequest can provide data synchronously.
     base::ThreadTaskRunnerHandle::Get()->PostTask(
         FROM_HERE,
         base::Bind(&ResourceLoader::OnReadCompleted,
@@ skipping 161 matching lines @@
       UMA_HISTOGRAM_ENUMERATION("Net.Prefetch.Pattern", prefetch_status,
                                 STATUS_MAX);
     }
   } else if (request_->response_info().unused_since_prefetch) {
     TimeDelta total_time = base::TimeTicks::Now() - request_->creation_time();
     UMA_HISTOGRAM_TIMES("Net.Prefetch.TimeSpentOnPrefetchHit", total_time);
   }
 }
 
 }  // namespace content