Disable zoom-in and zoom-out buttons in toolbar menu for a crashed page.

chrome/browser/ui/browser_commands.cc

 // Copyright 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 "chrome/browser/ui/browser_commands.h"
 
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
@@ skipping 556 matching lines @@
     // See http://crbug.com/6380.
     b->tab_strip_model()->GetActiveWebContents()->RestoreFocus();
   }
 }
 
 void CloseTab(Browser* browser) {
   content::RecordAction(UserMetricsAction("CloseTab_Accelerator"));
   browser->tab_strip_model()->CloseSelectedTabs();
 }
 
+int GetZoomPercent(content::WebContents* contents) {
+  int zoom = 100;
+  if (contents) {
+    auto zoom_controller =
+      ui_zoom::ZoomController::FromWebContents(contents);
+    if (zoom_controller)
+      zoom = zoom_controller->GetZoomPercent();
+  }
+  return zoom;
+}
+
 bool CanZoomIn(content::WebContents* contents) {
-  ui_zoom::ZoomController* zoom_controller =
-      ui_zoom::ZoomController::FromWebContents(contents);
-  return zoom_controller->GetZoomPercent() != contents->GetMaximumZoomPercent();
+  return contents && !contents->IsCrashed() &&
+      GetZoomPercent(contents) != contents->GetMaximumZoomPercent();
 }
 
 bool CanZoomOut(content::WebContents* contents) {
-  ui_zoom::ZoomController* zoom_controller =
-      ui_zoom::ZoomController::FromWebContents(contents);
-  return zoom_controller->GetZoomPercent() !=
-      contents->GetMinimumZoomPercent();
+  return contents && !contents->IsCrashed() &&
+      GetZoomPercent(contents) != contents->GetMinimumZoomPercent();
 }
 
 bool CanResetZoom(content::WebContents* contents) {
   ui_zoom::ZoomController* zoom_controller =
       ui_zoom::ZoomController::FromWebContents(contents);
   return !zoom_controller->IsAtDefaultZoom() ||
          !zoom_controller->PageScaleFactorIsOne();
 }
 
 TabStripModelDelegate::RestoreTabType GetRestoreTabType(
@@ skipping 688 matching lines @@
       app_name, true /* trusted_source */, gfx::Rect(), browser->profile()));
   app_browser->tab_strip_model()->AppendWebContents(contents, true);
 
   contents->GetMutableRendererPrefs()->can_accept_load_drops = false;
   contents->GetRenderViewHost()->SyncRendererPrefs();
   app_browser->window()->Show();
 }
 #endif  // defined(ENABLE_EXTENSIONS)
 
 }  // namespace chrome