Make sure manifest specified shortcut for Extension Command can not override the built-in shortcuts.

chrome/browser/ui/views/extensions/extension_keybinding_registry_views.cc

Index: chrome/browser/ui/views/extensions/extension_keybinding_registry_views.cc
diff --git a/chrome/browser/ui/views/extensions/extension_keybinding_registry_views.cc b/chrome/browser/ui/views/extensions/extension_keybinding_registry_views.cc
index 1531847118ccc1914d64dc2bafac94b97d16b4ba..518f1f96c4bfc4e78e2e642d8cd19b7d353a619d 100644
--- a/chrome/browser/ui/views/extensions/extension_keybinding_registry_views.cc
+++ b/chrome/browser/ui/views/extensions/extension_keybinding_registry_views.cc
@@ -8,6 +8,7 @@
 #include "chrome/browser/extensions/extension_keybinding_registry.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/ui/views/accelerator_table.h"
 #include "chrome/common/extensions/extension.h"
 #include "ui/views/focus/focus_manager.h"
 
@@ -17,6 +18,20 @@ void extensions::ExtensionKeybindingRegistry::SetShortcutHandlingSuspended(
   views::FocusManager::set_shortcut_handling_suspended(suspended);
 }
 
+// static
+bool extensions::ExtensionKeybindingRegistry::IsChromeAccelerator(
+    const ui::Accelerator& accelerator) {
+  std::vector<chrome::AcceleratorMapping> accelerators =
+      chrome::GetAcceleratorList();
+  for (std::vector<chrome::AcceleratorMapping>::const_iterator it =
+       accelerators.begin(); it != accelerators.end(); ++it) {
+    if (it->keycode == accelerator.key_code() &&
+        it->modifiers == accelerator.modifiers())
+      return true;
+  }
+  return false;
+}
+
 ExtensionKeybindingRegistryViews::ExtensionKeybindingRegistryViews(
     Profile* profile,
     views::FocusManager* focus_manager,