Avoids centering docked windows, Unsnaps when centering.

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 f761acb721e26ca11f9439431a32ed91097fc1cf..94494123619ffa08744dedc554b9097636b23652 100644
--- a/ash/accelerators/accelerator_controller.cc
+++ b/ash/accelerators/accelerator_controller.cc
@@ -842,7 +842,7 @@ bool AcceleratorController::PerformAction(int action,
     case WINDOW_SNAP_LEFT:
     case WINDOW_SNAP_RIGHT: {
       wm::WindowState* window_state = wm::GetActiveWindowState();
-      // Disable window docking shortcut key for full screen window due to
+      // Disable window snapping shortcut key for full screen window due to
       // http://crbug.com/135487.
       if (!window_state ||
           window_state->window()->type() != aura::client::WINDOW_TYPE_NORMAL ||
@@ -871,7 +871,10 @@ bool AcceleratorController::PerformAction(int action,
     }
     case WINDOW_POSITION_CENTER: {
       aura::Window* window = wm::GetActiveWindow();
-      if (window) {
+      // Centering a window does not maintain state and state change
+      // notifications are not sent. Disable centering for docked windows.

[pkotwicz, 2013/11/21 23:46:50]

I find it hard to understand the comment. This may be clearer:
"DockedWindowLayoutManager does not support windows leaving the dock as a result
of a bounds change outside the context of a drag. Disable centering for docked
windows."

[varkha, 2013/11/22 03:43:38]

Done.

+      content::RecordAction(content::UserMetricsAction("Accel_Center"));
+      if (window && !wm::GetWindowState(window)->IsDocked()) {
         wm::CenterWindow(window);
         return true;
       }