Rename GetRootWindow() -> GetPrimaryRootWindow()

ash/wm/screen_dimmer_unittest.cc

Index: ash/wm/screen_dimmer_unittest.cc
diff --git a/ash/wm/screen_dimmer_unittest.cc b/ash/wm/screen_dimmer_unittest.cc
index 8b7b58fc682f18cf8d6f0f60cee4aec611bd9385..ecc6cd5085d39f1ecc7fa8563aa4da1dc0c2d40f 100644
--- a/ash/wm/screen_dimmer_unittest.cc
+++ b/ash/wm/screen_dimmer_unittest.cc
@@ -44,7 +44,7 @@ TEST_F(ScreenDimmerTest, DimAndUndim) {
   // of the root's children.
   dimmer_->SetDimming(true);
   ASSERT_TRUE(test_api_->layer() != NULL);
-  ui::Layer* root_layer = Shell::GetInstance()->GetRootWindow()->layer();
+  ui::Layer* root_layer = Shell::GetPrimaryRootWindow()->layer();
   ASSERT_TRUE(!root_layer->children().empty());
   EXPECT_EQ(test_api_->layer(), root_layer->children().back());
   EXPECT_TRUE(test_api_->layer()->visible());
@@ -63,14 +63,14 @@ TEST_F(ScreenDimmerTest, ResizeLayer) {
   dimmer_->SetDimming(true);
   ui::Layer* dimming_layer = test_api_->layer();
   ASSERT_TRUE(dimming_layer != NULL);
-  ui::Layer* root_layer = Shell::GetInstance()->GetRootWindow()->layer();
+  ui::Layer* root_layer = Shell::GetPrimaryRootWindow()->layer();
   EXPECT_EQ(gfx::Rect(root_layer->bounds().size()).ToString(),
             dimming_layer->bounds().ToString());
 
   // When we resize the root window, the dimming layer should be resized to
   // match.
   gfx::Size kNewSize(400, 300);
-  Shell::GetInstance()->GetRootWindow()->SetHostSize(kNewSize);
+  Shell::GetPrimaryRootWindow()->SetHostSize(kNewSize);
   EXPECT_EQ(kNewSize.ToString(), dimming_layer->bounds().size().ToString());
 }