Implement "pinned" mode in ash.

ash/accelerators/accelerator_controller.cc

Index: ash/accelerators/accelerator_controller.cc
diff --git a/ash/accelerators/accelerator_controller.cc b/ash/accelerators/accelerator_controller.cc
index 23fa5d27f031f5feb927e843388b2b2334fe2509..b3309d24f12a9c6a67844a71793dd659f9cbd2aa 100644
--- a/ash/accelerators/accelerator_controller.cc
+++ b/ash/accelerators/accelerator_controller.cc
@@ -921,6 +921,8 @@ void AcceleratorController::Init() {
     actions_needing_window_.insert(kActionsNeedingWindow[i]);
   for (size_t i = 0; i < kActionsKeepingMenuOpenLength; ++i)
     actions_keeping_menu_open_.insert(kActionsKeepingMenuOpen[i]);
+  for (size_t i = 0; i < kActionsAllowedInPinnedModeLength; ++i)
+    actions_allowed_in_pinned_mode_.insert(kActionsAllowedInPinnedMode[i]);
 
   RegisterAccelerators(kAcceleratorData, kAcceleratorDataLength);
 
@@ -1399,6 +1401,11 @@ bool AcceleratorController::ShouldActionConsumeKeyEvent(
 
 AcceleratorController::AcceleratorProcessingRestriction
 AcceleratorController::GetAcceleratorProcessingRestriction(int action) {
+  if (WmShell::Get()->IsPinned() &&
+      actions_allowed_in_pinned_mode_.find(action) ==
+          actions_allowed_in_pinned_mode_.end()) {
+    return RESTRICTION_PREVENT_PROCESSING_AND_PROPAGATION;
+  }
   ash::Shell* shell = ash::Shell::GetInstance();
   if (!shell->session_state_delegate()->IsActiveUserSessionStarted() &&
       actions_allowed_at_login_screen_.find(action) ==