alternate ntp: implement Show/HideBars API to reduce jank when showing/hiding bars

chrome/common/render_messages.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.
 
 // Multiply-included file, no traditional include guard.
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
 
@@ skipping 294 matching lines @@
 IPC_MESSAGE_ROUTED1(ChromeViewMsg_SearchBoxCancel,
                     string16 /* value */)
 
 IPC_MESSAGE_ROUTED1(ChromeViewMsg_SearchBoxPopupResize,
                     gfx::Rect /* bounds */)
 
 IPC_MESSAGE_ROUTED2(ChromeViewMsg_SearchBoxMarginChange,
                     int /* start */,
                     int /* end */)
 
+IPC_MESSAGE_ROUTED0(ChromeViewMsg_SearchBoxBarsHidden)
+
 IPC_MESSAGE_ROUTED0(ChromeViewMsg_DetermineIfPageSupportsInstant)
 
 IPC_MESSAGE_ROUTED1(ChromeViewMsg_SearchBoxAutocompleteResults,
                     std::vector<InstantAutocompleteResult>
                         /* native_suggestions */)
 
 IPC_MESSAGE_ROUTED1(ChromeViewMsg_SearchBoxUpOrDownKeyPressed,
                     int /* count */)
 
 IPC_MESSAGE_ROUTED1(ChromeViewMsg_SearchBoxCancelSelection,
@@ skipping 366 matching lines @@
 // Sent by the Instant overlay asking to show itself with the given height.
 IPC_MESSAGE_ROUTED3(ChromeViewHostMsg_ShowInstantOverlay,
                     int /* page_id */,
                     int /* height */,
                     InstantSizeUnits /* units */)
 
 // Sent by Instant to focus the omnibox.
 IPC_MESSAGE_ROUTED1(ChromeViewHostMsg_FocusOmnibox,
                     int /* page_id */)
 
+// Sent by Instant to show any attached bars.
+IPC_MESSAGE_ROUTED1(ChromeViewHostMsg_SearchBoxShowBars,
+                    int /* page_id */)
+
+// Sent by Instant to hide any attached bars.
+IPC_MESSAGE_ROUTED1(ChromeViewHostMsg_SearchBoxHideBars,
+                    int /* page_id */)
+
 IPC_MESSAGE_ROUTED1(ChromeViewHostMsg_StartCapturingKeyStrokes,
                     int /* page_id */)
 
 IPC_MESSAGE_ROUTED1(ChromeViewHostMsg_StopCapturingKeyStrokes,
                     int /* page_id */)
 
 // The currently displayed PDF has an unsupported feature.
 IPC_MESSAGE_ROUTED0(ChromeViewHostMsg_PDFHasUnsupportedFeature)
 
 // This message indicates the error appeared in the frame.
@@ skipping 16 matching lines @@
 // previous SetCookie message to be processed.
 IPC_SYNC_MESSAGE_ROUTED2_1(ChromeViewHostMsg_GetCookies,
                            GURL /* url */,
                            GURL /* first_party_for_cookies */,
                            std::string /* cookies */)
 
 // Provide the browser process with current renderer framerate.
 IPC_MESSAGE_CONTROL2(ChromeViewHostMsg_FPS,
                      int /* routing id */,
                      float /* frames per second */)