Add multiline braille support.

chrome/browser/extensions/api/braille_display_private/braille_display_private_api.cc

 // Copyright 2013 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 "chrome/browser/extensions/api/braille_display_private/braille_display_private_api.h"
 
 #include <utility>
 
 #include "base/lazy_instance.h"
 #include "build/build_config.h"
@@ skipping 150 matching lines @@
 BrailleDisplayPrivateWriteDotsFunction::
 BrailleDisplayPrivateWriteDotsFunction() {
 }
 
 BrailleDisplayPrivateWriteDotsFunction::
 ~BrailleDisplayPrivateWriteDotsFunction() {
 }
 
 bool BrailleDisplayPrivateWriteDotsFunction::Prepare() {
   params_ = WriteDots::Params::Create(*args_);
   EXTENSION_FUNCTION_VALIDATE(params_);

[Devlin, 2016/11/02 15:10:30]

Can we either EXTENSION_FUNCTION_VALIDATE or throw an error on failure that
`params_->cells.size() >= params_->columns * params_->rows`?

Otherwise if we're passed bad input we'll read past the end of the vector and
have bad times.

[ultimatedbz, 2016/11/03 19:28:54]

Didn't really account for this in braille_controller_brlapi.cc?
+    unsigned int row_limit = std::min(rows, cells_rows);
+    unsigned int col_limit = std::min(columns, cells_cols);

If params_->cells.size() is too big, it just tapers off. If I were to
EXTENSION_FUNCTION_VALIDATE, where would I write this code? Thanks! 

[dmazzoni, 2016/11/04 18:10:35]

I think he's saying that if (params_->cells.size() >= params_->columns *
params_->rows) is not true, it shouldn't validate.

In other words, it should fail if you try to pass a vector that's not as large
as you say its dimensions are

Just call EXTENSION_FUNCTION_VALIDATE again:

EXTENSION_FUNCTION_VALIDATE(
    params_->cells.size() >= params_->columns * params_->rows);

[ultimatedbz, 2016/11/04 21:13:00]

Done.

   return true;
 }
 
 void BrailleDisplayPrivateWriteDotsFunction::Work() {
-  BrailleController::GetInstance()->WriteDots(params_->cells);
+  BrailleController::GetInstance()->WriteDots(params_->cells, params_->columns,
+                                              params_->rows);
 }
 
 bool BrailleDisplayPrivateWriteDotsFunction::Respond() {
   return true;
 }
 }  // namespace api
 }  // namespace extensions