Fix DownloadResourceHandler::OnReadCompleted to defer loading after consuming

the given data (and releasing read_buffer_).  The existing code was ignoring
a chunk of data and then crashing after the next call to OnWillRead.  The
crash was caused by OnWillRead failing to set *buf_size when read_buffer_ is
non-null.  That case was only possible when OnReadCompleted returned early.

This is fallout from http://crrev.com/144873, which changed the pause/resume
semantics such that deferring from OnReadCompleted pauses future network
events instead of pausing the current network event and future network events.
In other words, the DownloadResourceHandler still expected OnReadCompleted to
be called again upon resuming resource loading.

R=jam@chromium.org
BUG=137337
Review URL: https://chromiumcodereview.appspot.com/10804011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@147305 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 8 insertions, 10 deletions

diff --git a/content/browser/download/download_resource_handler.cc b/content/browser/download/download_resource_handler.cc
index cc2bc40..e42d0b4 100644
--- a/content/browser/download/download_resource_handler.cc
+++ b/content/browser/download/download_resource_handler.cc
@@ -237,11 +237,11 @@ bool DownloadResourceHandler::OnWillRead(int request_id, net::IOBuffer** buf,
                                          int* buf_size, int min_size) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   DCHECK(buf && buf_size);
-  if (!read_buffer_) {
-    *buf_size = min_size < 0 ? kReadBufSize : min_size;
-    last_buffer_size_ = *buf_size;
-    read_buffer_ = new net::IOBuffer(*buf_size);
-  }
+  DCHECK(!read_buffer_);
+
+  *buf_size = min_size < 0 ? kReadBufSize : min_size;
+  last_buffer_size_ = *buf_size;
+  read_buffer_ = new net::IOBuffer(*buf_size);
   *buf = read_buffer_.get();
   return true;
 }
@@ -252,11 +252,6 @@ bool DownloadResourceHandler::OnReadCompleted(int request_id, int bytes_read,
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   DCHECK(read_buffer_);
 
-  if (pause_count_ > 0) {
-    *defer = was_deferred_ = true;
-    return true;
-  }
-
   base::TimeTicks now(base::TimeTicks::Now());
   if (!last_read_time_.is_null()) {
     double seconds_since_last_read = (now - last_read_time_).InSecondsF();
@@ -286,6 +281,9 @@ bool DownloadResourceHandler::OnReadCompleted(int request_id, int bytes_read,
 
   read_buffer_ = NULL;  // Drop our reference.
 
+  if (pause_count_ > 0)
+    *defer = was_deferred_ = true;
+
   return true;
 }