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

chrome/browser/extensions/api/commands/command_service.cc

Index: chrome/browser/extensions/api/commands/command_service.cc
diff --git a/chrome/browser/extensions/api/commands/command_service.cc b/chrome/browser/extensions/api/commands/command_service.cc
index 62a4b37a559d97befb075ab756b0aca0837ab118..7355e76aebf36b372db4b5854164b6411d062758 100644
--- a/chrome/browser/extensions/api/commands/command_service.cc
+++ b/chrome/browser/extensions/api/commands/command_service.cc
@@ -232,37 +232,49 @@ void CommandService::AssignInitialKeybindings(const Extension* extension) {
 
   extensions::CommandMap::const_iterator iter = commands->begin();
   for (; iter != commands->end(); ++iter) {
-    AddKeybindingPref(iter->second.accelerator(),
-                      extension->id(),
-                      iter->second.command_name(),
-                      false);  // Overwriting not allowed.
+    if (!ExtensionKeybindingRegistry::IsChromeAccelerator(
+        iter->second.accelerator())) {
+      AddKeybindingPref(iter->second.accelerator(),
+                        extension->id(),
+                        iter->second.command_name(),
+                        false);  // Overwriting not allowed.
+    }
   }
 
   const extensions::Command* browser_action_command =
       CommandsInfo::GetBrowserActionCommand(extension);
   if (browser_action_command) {
-    AddKeybindingPref(browser_action_command->accelerator(),
-                      extension->id(),
-                      browser_action_command->command_name(),
-                      false);  // Overwriting not allowed.
+    if (!ExtensionKeybindingRegistry::IsChromeAccelerator(
+        browser_action_command->accelerator())) {
+      AddKeybindingPref(browser_action_command->accelerator(),
+                        extension->id(),
+                        browser_action_command->command_name(),
+                        false);  // Overwriting not allowed.
+    }
   }
 
   const extensions::Command* page_action_command =
       CommandsInfo::GetPageActionCommand(extension);
   if (page_action_command) {
-    AddKeybindingPref(page_action_command->accelerator(),
-                      extension->id(),
-                      page_action_command->command_name(),
-                      false);  // Overwriting not allowed.
+    if (!ExtensionKeybindingRegistry::IsChromeAccelerator(
+        page_action_command->accelerator())) {
+      AddKeybindingPref(page_action_command->accelerator(),
+                        extension->id(),
+                        page_action_command->command_name(),
+                        false);  // Overwriting not allowed.
+    }
   }
 
   const extensions::Command* script_badge_command =
       CommandsInfo::GetScriptBadgeCommand(extension);
   if (script_badge_command) {
-    AddKeybindingPref(script_badge_command->accelerator(),
-                      extension->id(),
-                      script_badge_command->command_name(),
-                      false);  // Overwriting not allowed.
+    if (!ExtensionKeybindingRegistry::IsChromeAccelerator(
+        script_badge_command->accelerator())) {
+      AddKeybindingPref(script_badge_command->accelerator(),
+                        extension->id(),
+                        script_badge_command->command_name(),
+                        false);  // Overwriting not allowed.
+    }
   }
 }