Don't animate the download shelf when entering/exiting fullscreen.

chrome/browser/ui/exclusive_access/fullscreen_controller.cc

 // 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.
 
 #include "chrome/browser/ui/exclusive_access/fullscreen_controller.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/location.h"
 #include "base/metrics/histogram_macros.h"
@@ skipping 220 matching lines @@
 }
 
 void FullscreenController::OnTabClosing(WebContents* web_contents) {
   if (IsFullscreenForCapturedTab(web_contents))
     web_contents->ExitFullscreen(
         /* will_cause_resize */ IsFullscreenCausedByTab());
   else
     ExclusiveAccessControllerBase::OnTabClosing(web_contents);
 }
 
+void FullscreenController::WindowFullscreenStateWillChange() {
+  auto* exclusive_access_context = exclusive_access_manager()->context();

[Nico, 2017/02/17 15:53:46]

nit: style guide says "only use auto if type obvious"

[Sidney San Martín, 2017/02/17 16:07:08]

Done.

+  if (exclusive_access_context->IsFullscreen()) {
+    exclusive_access_context->HideDownloadShelf();
+  } else {
+    exclusive_access_context->UnhideDownloadShelf();
+  }
+}
+
 void FullscreenController::WindowFullscreenStateChanged() {
   reentrant_window_state_change_call_check_ = true;
   ExclusiveAccessContext* const exclusive_access_context =
       exclusive_access_manager()->context();
   bool exiting_fullscreen = !exclusive_access_context->IsFullscreen();
 
   PostFullscreenChangeNotification(!exiting_fullscreen);
   if (exiting_fullscreen) {
     toggled_into_fullscreen_ = false;
     extension_caused_fullscreen_ = GURL();
     NotifyTabExclusiveAccessLost();
-    exclusive_access_context->UnhideDownloadShelf();
-  } else {
-    exclusive_access_context->HideDownloadShelf();
   }
 }
 
 bool FullscreenController::HandleUserPressedEscape() {
   WebContents* const active_web_contents =
       exclusive_access_manager()->context()->GetActiveWebContents();
   if (IsFullscreenForCapturedTab(active_web_contents)) {
     active_web_contents->ExitFullscreen(
         /* will_cause_resize */ IsFullscreenCausedByTab());
     return true;
@@ skipping 182 matching lines @@
     return fullscreened_origin_;
 
   return exclusive_access_tab()->GetLastCommittedURL();
 }
 
 GURL FullscreenController::GetEmbeddingOrigin() const {
   DCHECK(exclusive_access_tab());
 
   return exclusive_access_tab()->GetLastCommittedURL();
 }