Rename ash desktop_background to wallpaper.

Move and rename ash/desktop_background/*
Move and rename ash/wm/system_background_controller*
Rename identifiers; update comments.

Remove unused src_container for Reparent* functions.

BUG=629605
TEST=No functional changes; just renaming.
[email protected]
[email protected],[email protected],[email protected]

Review-Url: https://codereview.chromium.org/2290473004
Cr-Commit-Position: refs/heads/master@{#415335}
diff --git a/ash/root_window_controller_unittest.cc b/ash/root_window_controller_unittest.cc
index 2461282..fab81b83 100644
--- a/ash/root_window_controller_unittest.cc
+++ b/ash/root_window_controller_unittest.cc
@@ -300,28 +300,28 @@
 
   UpdateDisplay("500x500");
   const int kLockScreenWindowId = 1000;
-  const int kLockBackgroundWindowId = 1001;
+  const int kLockWallpaperWindowId = 1001;
 
   RootWindowController* controller = Shell::GetPrimaryRootWindowController();
 
   aura::Window* lock_container =
       controller->GetContainer(kShellWindowId_LockScreenContainer);
-  aura::Window* lock_background_container =
-      controller->GetContainer(kShellWindowId_LockScreenBackgroundContainer);
+  aura::Window* lock_wallpaper_container =
+      controller->GetContainer(kShellWindowId_LockScreenWallpaperContainer);
 
   views::Widget* lock_screen =
       CreateModalWidgetWithParent(gfx::Rect(10, 10, 100, 100), lock_container);
   lock_screen->GetNativeWindow()->set_id(kLockScreenWindowId);
   lock_screen->SetFullscreen(true);
 
-  views::Widget* lock_background = CreateModalWidgetWithParent(
-      gfx::Rect(10, 10, 100, 100), lock_background_container);
-  lock_background->GetNativeWindow()->set_id(kLockBackgroundWindowId);
+  views::Widget* lock_wallpaper = CreateModalWidgetWithParent(
+      gfx::Rect(10, 10, 100, 100), lock_wallpaper_container);
+  lock_wallpaper->GetNativeWindow()->set_id(kLockWallpaperWindowId);
 
   ASSERT_EQ(lock_screen->GetNativeWindow(),
             controller->GetRootWindow()->GetChildById(kLockScreenWindowId));
-  ASSERT_EQ(lock_background->GetNativeWindow(),
-            controller->GetRootWindow()->GetChildById(kLockBackgroundWindowId));
+  ASSERT_EQ(lock_wallpaper->GetNativeWindow(),
+            controller->GetRootWindow()->GetChildById(kLockWallpaperWindowId));
   EXPECT_EQ("0,0 500x500", lock_screen->GetNativeWindow()->bounds().ToString());
 
   // Switch to unified.
@@ -332,8 +332,8 @@
 
   ASSERT_EQ(lock_screen->GetNativeWindow(),
             controller->GetRootWindow()->GetChildById(kLockScreenWindowId));
-  ASSERT_EQ(lock_background->GetNativeWindow(),
-            controller->GetRootWindow()->GetChildById(kLockBackgroundWindowId));
+  ASSERT_EQ(lock_wallpaper->GetNativeWindow(),
+            controller->GetRootWindow()->GetChildById(kLockWallpaperWindowId));
   EXPECT_EQ("0,0 500x500", lock_screen->GetNativeWindow()->bounds().ToString());
 
   // Switch to mirror.
@@ -344,8 +344,8 @@
   controller = Shell::GetPrimaryRootWindowController();
   ASSERT_EQ(lock_screen->GetNativeWindow(),
             controller->GetRootWindow()->GetChildById(kLockScreenWindowId));
-  ASSERT_EQ(lock_background->GetNativeWindow(),
-            controller->GetRootWindow()->GetChildById(kLockBackgroundWindowId));
+  ASSERT_EQ(lock_wallpaper->GetNativeWindow(),
+            controller->GetRootWindow()->GetChildById(kLockWallpaperWindowId));
   EXPECT_EQ("0,0 500x500", lock_screen->GetNativeWindow()->bounds().ToString());
 
   // Switch to unified.
@@ -356,8 +356,8 @@
 
   ASSERT_EQ(lock_screen->GetNativeWindow(),
             controller->GetRootWindow()->GetChildById(kLockScreenWindowId));
-  ASSERT_EQ(lock_background->GetNativeWindow(),
-            controller->GetRootWindow()->GetChildById(kLockBackgroundWindowId));
+  ASSERT_EQ(lock_wallpaper->GetNativeWindow(),
+            controller->GetRootWindow()->GetChildById(kLockWallpaperWindowId));
   EXPECT_EQ("0,0 500x500", lock_screen->GetNativeWindow()->bounds().ToString());
 
   // Switch to single display.
@@ -369,8 +369,8 @@
 
   ASSERT_EQ(lock_screen->GetNativeWindow(),
             controller->GetRootWindow()->GetChildById(kLockScreenWindowId));
-  ASSERT_EQ(lock_background->GetNativeWindow(),
-            controller->GetRootWindow()->GetChildById(kLockBackgroundWindowId));
+  ASSERT_EQ(lock_wallpaper->GetNativeWindow(),
+            controller->GetRootWindow()->GetChildById(kLockWallpaperWindowId));
   EXPECT_EQ("0,0 600x500", lock_screen->GetNativeWindow()->bounds().ToString());
 }