Updates Zoom bubble layout and adds +/- buttons

components/zoom/zoom_controller.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 "components/zoom/zoom_controller.h"
 
 #include "components/zoom/zoom_event_manager.h"
 #include "components/zoom/zoom_observer.h"
 #include "content/public/browser/host_zoom_map.h"
 #include "content/public/browser/navigation_details.h"
@@ skipping 329 matching lines @@
       return;
     }
   }
 
   if (event_data_) {
     // For state changes initiated within the ZoomController, information about
     // the change should be sent.
     ZoomChangedEventData zoom_change_data = *event_data_;
     event_data_.reset();
     // The zoom bubble should not be shown for zoom changes where the host
-    // is empty.
-    zoom_change_data.can_show_bubble = can_show_bubble_ && !host.empty();
+    // is empty or when zoom level is not changed from default.
+    const bool changed_from_default =
+        zoom_change_data.new_zoom_level != zoom_change_data.old_zoom_level ||
+        zoom_change_data.new_zoom_level != GetDefaultZoomLevel();
+    zoom_change_data.can_show_bubble =
+        can_show_bubble_ && !host.empty() && changed_from_default;
     for (auto& observer : observers_)
       observer.OnZoomChanged(zoom_change_data);
   } else {
     // TODO(wjmaclean) Should we consider having HostZoomMap send both old and
     // new zoom levels here?
     double zoom_level = GetZoomLevel();
     // We never show a zoom bubble for an event we didn't generate.
     ZoomChangedEventData zoom_change_data(web_contents(), zoom_level,
                                           zoom_level, zoom_mode_,
                                           false /* can_show_bubble */);
     for (auto& observer : observers_)
       observer.OnZoomChanged(zoom_change_data);
   }
 }
 
 void ZoomController::SetPageScaleFactorIsOneForTesting(bool is_one) {
   int render_process_id = web_contents()->GetRenderProcessHost()->GetID();
   int render_view_id = web_contents()->GetRenderViewHost()->GetRoutingID();
   host_zoom_map_->SetPageScaleFactorIsOneForView(render_process_id,
                                                  render_view_id, is_one);
 }
 
 bool ZoomController::PageScaleFactorIsOne() const {
   return content::HostZoomMap::PageScaleFactorIsOne(web_contents());
 }
 
 }  // namespace zoom