Make most browser accelerators not repeat.

chrome/browser/ui/views/frame/browser_view.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_VIEWS_FRAME_BROWSER_VIEW_H_
 #define CHROME_BROWSER_UI_VIEWS_FRAME_BROWSER_VIEW_H_
 
 #include <map>
 #include <memory>
 #include <string>
@@ skipping 639 matching lines @@
   views::View* contents_container_;
 
   // Tracks and stores the last focused view which is not the
   // devtools_web_view_ or any of its children. Used to restore focus once
   // the devtools_web_view_ is hidden.
   std::unique_ptr<views::ExternalFocusTracker> devtools_focus_tracker_;
 
   // The Status information bubble that appears at the bottom of the window.
   std::unique_ptr<StatusBubbleViews> status_bubble_;
 
-  // A mapping between accelerators and commands.
+  // A mapping between accelerators and command IDs.
   std::map<ui::Accelerator, int> accelerator_table_;
 
+  // IDs of commands that should be executed in response to repeated
+  // accelerators (i.e. generated by holding keys down). Repeated accelerators
+  // are ignored otherwise.
+  std::set<int> repeatable_command_ids_;

[sky, 2016/09/01 19:31:06]

How often do we trigger accelerators, especially ones with a repeat? My
suspicion is it isn't worth caching this. WDYT?

[Daniel Erat, 2016/09/01 19:47:31]

the local copy was initially due to mirroring the accelerator_table_ code. it
feels weird to initialize a new set every time we see a repeatable accelerator
(especially since these come in quickly if they're being repeated), but at the
same time, it's small and we're probably doing much bigger allocations for other
reasons.

i'd prefer to leave this, but i'll remove it if you really want me to. :-)

but one other option would be instead have an chrome::IsCommandRepeatable()
function be exposed by accelerator_table.h. it could just iterate through the
few entries in its local array every time it's called.

+
   // True if we have already been initialized.
   bool initialized_;
 
   // True if we're currently handling a theme change (i.e. inside
   // OnThemeChanged()).
   bool handling_theme_changed_;
 
   // True when in ProcessFullscreen(). The flag is used to avoid reentrance and
   // to ignore requests to layout while in ProcessFullscreen() to reduce
   // jankiness.
@@ skipping 30 matching lines @@
   // The class that registers for keyboard shortcuts for extension commands.
   std::unique_ptr<ExtensionKeybindingRegistryViews>
       extension_keybinding_registry_;
 
   mutable base::WeakPtrFactory<BrowserView> activate_modal_dialog_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserView);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_FRAME_BROWSER_VIEW_H_