Get rid of the huge delay in background resize during rotation

ash/desktop_background/desktop_background_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 "ash/desktop_background/desktop_background_controller.h"
 
 #include "ash/ash_switches.h"
 #include "ash/desktop_background/desktop_background_controller_observer.h"
 #include "ash/desktop_background/desktop_background_view.h"
 #include "ash/desktop_background/desktop_background_widget_controller.h"
@@ skipping 27 matching lines @@
 using wallpaper::WALLPAPER_LAYOUT_CENTER;
 using wallpaper::WALLPAPER_LAYOUT_CENTER_CROPPED;
 using wallpaper::WALLPAPER_LAYOUT_STRETCH;
 using wallpaper::WALLPAPER_LAYOUT_TILE;
 
 namespace ash {
 namespace {
 
 // How long to wait reloading the wallpaper after the max display has
 // changed?
-const int kWallpaperReloadDelayMs = 2000;
+const int kWallpaperReloadDelayMs = 100;
 
 }  // namespace
 
 DesktopBackgroundController::DesktopBackgroundController()
     : locked_(false),
       desktop_background_mode_(BACKGROUND_NONE),
       wallpaper_reload_delay_(kWallpaperReloadDelayMs) {
   Shell::GetInstance()->display_controller()->AddObserver(this);
   Shell::GetInstance()->AddShellObserver(this);
 }
@@ skipping 70 matching lines @@
 
 void DesktopBackgroundController::OnDisplayConfigurationChanged() {
   gfx::Size max_display_size = GetMaxDisplaySizeInNative();
   if (current_max_display_size_ != max_display_size) {
     current_max_display_size_ = max_display_size;
     if (desktop_background_mode_ == BACKGROUND_IMAGE &&
         current_wallpaper_.get()) {
       timer_.Stop();
       timer_.Start(FROM_HERE,
                    base::TimeDelta::FromMilliseconds(wallpaper_reload_delay_),
-                   this,
-                   &DesktopBackgroundController::UpdateWallpaper);
+                   base::Bind(&DesktopBackgroundController::UpdateWallpaper,
+                              base::Unretained(this), false /* clear cache */));

[oshima, 2015/05/12 22:36:23]

Sorry if I wasn't clear. We shouldn't need any delay when rotated with 
accelerometer. Delay was added for when rotating using UI (shortcut / settings).

     }
   }
 }
 
 void DesktopBackgroundController::OnRootWindowAdded(aura::Window* root_window) {
   // The background hasn't been set yet.
   if (desktop_background_mode_ == BACKGROUND_NONE)
     return;
 
   // Handle resolution change for "built-in" images.
   gfx::Size max_display_size = GetMaxDisplaySizeInNative();
   if (current_max_display_size_ != max_display_size) {
     current_max_display_size_ = max_display_size;
     if (desktop_background_mode_ == BACKGROUND_IMAGE &&
         current_wallpaper_.get())
-      UpdateWallpaper();
+      UpdateWallpaper(true /* clear cache */);
   }
 
   InstallDesktopController(root_window);
 }
 
 // static
 gfx::Size DesktopBackgroundController::GetMaxDisplaySizeInNative() {
   int width = 0;
   int height = 0;
   std::vector<gfx::Display> displays = Shell::GetScreen()->GetAllDisplays();
@@ skipping 101 matching lines @@
     }
   }
   return moved;
 }
 
 int DesktopBackgroundController::GetBackgroundContainerId(bool locked) {
   return locked ? kShellWindowId_LockScreenBackgroundContainer
                 : kShellWindowId_DesktopBackgroundContainer;
 }
 
-void DesktopBackgroundController::UpdateWallpaper() {
+void DesktopBackgroundController::UpdateWallpaper(bool clear_cache) {
   current_wallpaper_.reset(NULL);
-  ash::Shell::GetInstance()->user_wallpaper_delegate()->
-      UpdateWallpaper(true /* clear cache */);
+  ash::Shell::GetInstance()->user_wallpaper_delegate()->UpdateWallpaper(
+      clear_cache);
 }
 
 }  // namespace ash