Track the active ExtensionKeybindingRegistry and make it available to EventRewriter.

chrome/browser/chromeos/events/event_rewriter.cc

 // Copyright 2014 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/chromeos/events/event_rewriter.h"
 
 #include <vector>
 
 #include "ash/sticky_keys/sticky_keys_controller.h"
 #include "ash/wm/window_state.h"
 #include "ash/wm/window_util.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/prefs/pref_service.h"
 #include "base/strings/string_util.h"
 #include "base/sys_info.h"
 #include "chrome/browser/chromeos/login/ui/login_display_host_impl.h"
 #include "chrome/browser/profiles/profile_manager.h"
+#include "chrome/browser/ui/browser.h"
+#include "chrome/browser/ui/browser_list.h"
+#include "chrome/browser/ui/browser_window.h"
 #include "chrome/common/pref_names.h"
 #include "chromeos/chromeos_switches.h"
 #include "chromeos/ime/ime_keyboard.h"
 #include "chromeos/ime/input_method_manager.h"
 #include "components/user_manager/user_manager.h"
 #include "ui/events/event.h"
 #include "ui/events/event_utils.h"
 #include "ui/events/keycodes/keyboard_code_conversion.h"
 #include "ui/wm/core/window_util.h"
 
@@ skipping 119 matching lines @@
     const ui::MouseEvent& event,
     scoped_ptr<ui::Event>* rewritten_event) {
   RewriteMouseButtonEvent(event, rewritten_event);
 }
 
 ui::EventRewriteStatus EventRewriter::RewriteEvent(
     const ui::Event& event,
     scoped_ptr<ui::Event>* rewritten_event) {
   if ((event.type() == ui::ET_KEY_PRESSED) ||
       (event.type() == ui::ET_KEY_RELEASED)) {
+    // Check the extensions system didn't bind any of these keys.

[Finnur, 2014/09/10 10:15:16]

I would do a few things here.

1) Add a helper function, IsExtensionCommandRegistered(event) and move almost
all of the new logic to that.

2) Change this function to read:

if ((event.type() == ui::ET_KEY_PRESSED) ||
    (event.type() == ui::ET_KEY_RELEASED)) {
  // Some keyboard events for ChromeOS get rewritten, such as:
  // Search+Shift+Left gets converted to Shift+Home (BeginDocument).
  // This doesn't make sense if the user has assigned that shortcut
  // to an extension. Because:
  // 1) The extension would, upon seeing a request for Ctrl+Shift+Home have
  //    to register for Shift+Home, instead.
  // 2) The conversion is unnecessary, because Shift+Home (BeginDocument) isn't
  //    going to be executed.
  // Therefore, we skip converting the accelerator if an extension has
  // registered for this shortcut.
  if (IsExtensionCommandRegistered(event)
    return ui::EVENT_REWRITE_CONTINUE;
  return RewriteKeyEvent(static_cast<const ui::KeyEvent&>(event),
}

3) Make sure I got the conversion correctly (Ctrl+Shift+Left is Shift+Home,
which is BeginDocument). 

+    const BrowserList* ash_browser_list =
+        BrowserList::GetInstance(chrome::HOST_DESKTOP_TYPE_ASH);
+    for (BrowserList::const_reverse_iterator browser_iterator =
+             ash_browser_list->begin_last_active();
+         browser_iterator != ash_browser_list->end_last_active();
+         ++browser_iterator) {
+      BrowserWindow* window = (*browser_iterator)->window();
+
+      if (window->IsActive()) {
+        int modifiers = ui::EF_NONE;
+        if (event.IsShiftDown())
+          modifiers |= ui::EF_SHIFT_DOWN;
+        if (event.IsControlDown())
+          modifiers |= ui::EF_CONTROL_DOWN;
+        if (event.IsAltDown())
+          modifiers |= ui::EF_ALT_DOWN;
+        if (event.IsCommandDown())
+          modifiers |= ui::EF_COMMAND_DOWN;
+        ui::Accelerator accelerator(
+            static_cast<const ui::KeyEvent&>(event).key_code(), modifiers);
+        if (window->IsExtensionCommandRegistered(accelerator))
+          return ui::EVENT_REWRITE_CONTINUE;
+      }
+    }
+
     return RewriteKeyEvent(static_cast<const ui::KeyEvent&>(event),
                            rewritten_event);
   }
   if ((event.type() == ui::ET_MOUSE_PRESSED) ||
       (event.type() == ui::ET_MOUSE_RELEASED)) {
     return RewriteMouseButtonEvent(static_cast<const ui::MouseEvent&>(event),
                                    rewritten_event);
   }
   if (event.type() == ui::ET_MOUSEWHEEL) {
     return RewriteMouseWheelEvent(
@@ skipping 692 matching lines @@
     KeyboardDeviceAddedInternal(device_info[i].deviceid, device_info[i].name);
   }
 
   XIFreeDeviceInfo(device_info);
 #else
   KeyboardDeviceAddedInternal(device_id, "keyboard");
 #endif
 }
 
 }  // namespace chromeos