Construct and check for mojo::Event's LocationData as needed.

components/pdf_viewer/pdf_viewer.cc

 // Copyright 2015 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 "base/bind.h"
 #include "base/callback.h"
 #include "base/containers/hash_tables.h"
 #include "base/memory/scoped_ptr.h"
 #include "components/mus/public/cpp/types.h"
 #include "components/mus/public/cpp/view.h"
@@ skipping 367 matching lines @@
     if (event->key_data &&
         (event->action != mojo::EVENT_TYPE_KEY_PRESSED ||
          event->key_data->is_char)) {
       return;
     }
 
     // TODO(rjkroege): Make panning and scrolling more performant and
     // responsive to gesture events.
     if ((event->key_data &&
          event->key_data->windows_key_code == mojo::KEYBOARD_CODE_DOWN) ||
-        (event->wheel_data && event->wheel_data &&
-         event->wheel_data->delta_y < 0)) {
+        (event->wheel_data && event->wheel_data->delta_y < 0)) {

[rjkroege, 2015/09/22 22:52:41]

my oops. 

       if (current_page_ < (page_count_ - 1)) {
         current_page_++;
         DrawBitmap(embedder_for_roots_[view]);
       }
     } else if ((event->key_data &&
                 event->key_data->windows_key_code == mojo::KEYBOARD_CODE_UP) ||
-               (event->pointer_data && event->wheel_data &&
-                event->wheel_data->delta_y > 0)) {
+               (event->wheel_data && event->wheel_data->delta_y > 0)) {
       if (current_page_ > 0) {
         current_page_--;
         DrawBitmap(embedder_for_roots_[view]);
       }
     }
   }
 
   void OnViewDestroyed(mus::View* view) override {
     DCHECK(embedder_for_roots_.find(view) != embedder_for_roots_.end());
     const auto& it = embedder_for_roots_.find(view);
@@ skipping 109 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(PDFViewer);
 };
 
 }  // namespace
 }  // namespace pdf_viewer
 
 MojoResult MojoMain(MojoHandle application_request) {
   mojo::ApplicationRunner runner(new pdf_viewer::PDFViewer());
   return runner.Run(application_request);
 }