net: FileStream::Read/Write() to take IOBuffer* instead of char*

content/browser/renderer_host/redirect_to_file_resource_handler.cc

Index: content/browser/renderer_host/redirect_to_file_resource_handler.cc
diff --git a/content/browser/renderer_host/redirect_to_file_resource_handler.cc b/content/browser/renderer_host/redirect_to_file_resource_handler.cc
index 8ebba69a259a904d9adbd1c44fc59e235b088735..5344b0663a34ffc909ee620c2706a20bba194f7a 100644
--- a/content/browser/renderer_host/redirect_to_file_resource_handler.cc
+++ b/content/browser/renderer_host/redirect_to_file_resource_handler.cc
@@ -36,7 +36,6 @@ RedirectToFileResourceHandler::RedirectToFileResourceHandler(
       request_id_(-1),
       buf_(new net::GrowableIOBuffer()),
       buf_write_pending_(false),
-      write_cursor_(0),
       write_callback_pending_(false),
       request_was_closed_(false),
       completed_during_write_(false) {
@@ -111,6 +110,17 @@ bool RedirectToFileResourceHandler::OnReadCompleted(int request_id,
   DCHECK(new_offset <= buf_->capacity());
   buf_->set_offset(new_offset);
 
+  // Reset the cursor per the new offset.
+  if (write_cursor_) {
+    // If we already have the write cursor, create a new one and advance
+    // to where we were.
+    int consumed_so_far = write_cursor_->BytesConsumed();
+    write_cursor_ = new net::DrainableIOBuffer(buf_, buf_->offset());
+    write_cursor_->DidConsume(consumed_so_far);
+  } else {
+    write_cursor_ = new net::DrainableIOBuffer(buf_, buf_->offset());
+  }
+
   if (BufIsFull())
     host_->PauseRequest(process_id_, request_id, true);
 
@@ -179,7 +189,7 @@ void RedirectToFileResourceHandler::DidWriteToFile(int result) {
   bool failed = false;
   if (result > 0) {
     next_handler_->OnDataDownloaded(request_id_, result);
-    write_cursor_ += result;
+    write_cursor_->DidConsume(result);
     failed = !WriteMore();
   } else {
     failed = true;
@@ -197,23 +207,22 @@ void RedirectToFileResourceHandler::DidWriteToFile(int result) {
 bool RedirectToFileResourceHandler::WriteMore() {
   DCHECK(file_stream_.get());
   for (;;) {
-    if (write_cursor_ == buf_->offset()) {
+    if (write_cursor_->BytesRemaining() == 0) {
       // We've caught up to the network load, but it may be in the process of
       // appending more data to the buffer.
       if (!buf_write_pending_) {
         if (BufIsFull())
           host_->PauseRequest(process_id_, request_id_, false);
         buf_->set_offset(0);
-        write_cursor_ = 0;
+        write_cursor_ = NULL;
       }
       return true;
     }
     if (write_callback_pending_)
       return true;
-    DCHECK(write_cursor_ < buf_->offset());
+    DCHECK_LT(0, write_cursor_->BytesRemaining());
     int rv = file_stream_->Write(
-        buf_->StartOfBuffer() + write_cursor_,
-        buf_->offset() - write_cursor_,
+        write_cursor_, write_cursor_->BytesRemaining(),
         base::Bind(&RedirectToFileResourceHandler::DidWriteToFile,
                    base::Unretained(this)));
     if (rv == net::ERR_IO_PENDING) {
@@ -223,7 +232,7 @@ bool RedirectToFileResourceHandler::WriteMore() {
     if (rv <= 0)
       return false;
     next_handler_->OnDataDownloaded(request_id_, rv);
-    write_cursor_ += rv;
+    write_cursor_->DidConsume(rv);
   }
 }