Reland of Add dimming to the background during sign in (patchset #1 id:1 of https://codereview.chromium.org/1424513003/ )

Reason for revert:
The asan issue has been fixed in the new CL https://codereview.chromium.org/1426573004/

Original issue's description:
> Revert of Add dimming to the background during sign in  (patchset #4 id:160001 of https://codereview.chromium.org/1400153002/ )
>
> Reason for revert:
> https://code.google.com/p/chromium/issues/detail?id=547178
>
> Original issue's description:
> > Add dimming to the background during sign in
> >
> > * Add option to put the dim layer at the bottom. Login screen put this dim layer at the bottom of login container containers so that
> >  dim layer stays during login transition.
> >
> > BUG=478438
> > TEST=ScreenDimmer.DimAtBottom
> >
> > Committed: https://crrev.com/c527600749bfc6970ba39e4ed6b24404b0f7b256
> > Cr-Commit-Position: refs/heads/master@{#355481}
>
> TBR=dzhioev@chromium.org,alemate@chromium.org,oshima@chromium.org
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=478438
>
> Committed: https://crrev.com/ccb7824284975a271967334f86b4fc7a17378de5
> Cr-Commit-Position: refs/heads/master@{#355885}

TBR=dzhioev@chromium.org,alemate@chromium.org,dalecurtis@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=478438

Review URL: https://codereview.chromium.org/1413523005

Cr-Commit-Position: refs/heads/master@{#356396}

5 files changed, 60 insertions, 2 deletions

diff --git a/ash/wm/screen_dimmer.cc b/ash/wm/screen_dimmer.cc
index 6c74888..559faaf 100644
--- a/ash/wm/screen_dimmer.cc
+++ b/ash/wm/screen_dimmer.cc
@@ -53,7 +53,10 @@ ScreenDimmer* ScreenDimmer::GetForRoot() {
 }
 
 ScreenDimmer::ScreenDimmer(int container_id)
-    : container_id_(container_id), target_opacity_(0.5f), is_dimming_(false) {
+    : container_id_(container_id),
+      target_opacity_(0.5f),
+      is_dimming_(false),
+      at_bottom_(false) {
   Shell::GetInstance()->AddShellObserver(this);
 }
 
@@ -93,6 +96,10 @@ void ScreenDimmer::Update(bool should_dim) {
         dim = new DimWindow(container);
         dim->SetDimOpacity(target_opacity_);
       }
+      if (at_bottom_)
+        dim->parent()->StackChildAtBottom(dim);
+      else
+        dim->parent()->StackChildAtTop(dim);
       dim->Show();
     } else {
       if (dim) {
diff --git a/ash/wm/screen_dimmer.h b/ash/wm/screen_dimmer.h
index 6d26e68..9d8779e 100644
--- a/ash/wm/screen_dimmer.h
+++ b/ash/wm/screen_dimmer.h
@@ -41,6 +41,8 @@ class ASH_EXPORT ScreenDimmer : ShellObserver {
   // Dim or undim the layers.
   void SetDimming(bool should_dim);
 
+  void set_at_bottom(bool at_bottom) { at_bottom_ = at_bottom; }
+
   bool is_dimming() const { return is_dimming_; }
 
   // Find a ScreenDimmer in the container, or nullptr if it does not exist.
@@ -63,6 +65,7 @@ class ASH_EXPORT ScreenDimmer : ShellObserver {
 
   // Are we currently dimming the screen?
   bool is_dimming_;
+  bool at_bottom_;
 
   DISALLOW_COPY_AND_ASSIGN(ScreenDimmer);
 };
diff --git a/ash/wm/screen_dimmer_unittest.cc b/ash/wm/screen_dimmer_unittest.cc
index 9b1bdc6..084105e 100644
--- a/ash/wm/screen_dimmer_unittest.cc
+++ b/ash/wm/screen_dimmer_unittest.cc
@@ -10,7 +10,8 @@
 #include "ash/wm/dim_window.h"
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
-#include "ui/aura/window_event_dispatcher.h"
+//#include "ui/aura/window_event_dispatcher.h"
+#include "ui/aura/test/test_windows.h"
 #include "ui/compositor/layer.h"
 
 namespace ash {
@@ -86,5 +87,29 @@ TEST_F(ScreenDimmerTest, RootDimmer) {
   EXPECT_EQ(nullptr, ScreenDimmer::FindForTest(-1));
 }
 
+TEST_F(ScreenDimmerTest, DimAtBottom) {
+  ScreenDimmer* root_dimmer = ScreenDimmer::GetForRoot();
+  aura::Window* root_window = Shell::GetPrimaryRootWindow();
+  scoped_ptr<aura::Window> window(
+      aura::test::CreateTestWindowWithId(1, root_window));
+  root_dimmer->SetDimming(true);
+  std::vector<aura::Window*>::const_iterator dim_iter =
+      std::find(root_window->children().begin(), root_window->children().end(),
+                GetDimWindow());
+  ASSERT_TRUE(dim_iter != root_window->children().end());
+  // Dim layer is at top.
+  EXPECT_EQ(*dim_iter, *root_window->children().rbegin());
+
+  root_dimmer->SetDimming(false);
+  root_dimmer->set_at_bottom(true);
+  root_dimmer->SetDimming(true);
+
+  dim_iter = std::find(root_window->children().begin(),
+                       root_window->children().end(), GetDimWindow());
+  ASSERT_TRUE(dim_iter != root_window->children().end());
+  // Dom layer is at the bottom.
+  EXPECT_EQ(*dim_iter, *root_window->children().begin());
+}
+
 }  // namespace test
 }  // namespace ash
diff --git a/chrome/browser/ui/webui/chromeos/login/oobe_ui.cc b/chrome/browser/ui/webui/chromeos/login/oobe_ui.cc
index 70fa6ee..d34af39 100644
--- a/chrome/browser/ui/webui/chromeos/login/oobe_ui.cc
+++ b/chrome/browser/ui/webui/chromeos/login/oobe_ui.cc
@@ -4,6 +4,8 @@
 
 #include "chrome/browser/ui/webui/chromeos/login/oobe_ui.h"
 
+#include "ash/shell_window_ids.h"
+#include "ash/wm/screen_dimmer.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
@@ -381,6 +383,9 @@ OobeUI::OobeUI(content::WebUI* web_ui, const GURL& url)
 OobeUI::~OobeUI() {
   core_handler_->SetDelegate(nullptr);
   network_dropdown_handler_->RemoveObserver(error_screen_handler_);
+  ash::ScreenDimmer::GetForContainer(
+      ash::kShellWindowId_LockScreenContainersContainer)
+      ->SetDimming(false);
 }
 
 CoreOobeActor* OobeUI::GetCoreOobeActor() {
@@ -539,6 +544,12 @@ void OobeUI::InitializeScreenMaps() {
   screen_names_[SCREEN_OOBE_HOST_PAIRING] = kScreenHostPairing;
   screen_names_[SCREEN_DEVICE_DISABLED] = kScreenDeviceDisabled;
 
+  dim_overlay_screen_ids_.push_back(SCREEN_CONFIRM_PASSWORD);
+  dim_overlay_screen_ids_.push_back(SCREEN_GAIA_SIGNIN);
+  dim_overlay_screen_ids_.push_back(SCREEN_OOBE_ENROLLMENT);
+  dim_overlay_screen_ids_.push_back(SCREEN_PASSWORD_CHANGED);
+  dim_overlay_screen_ids_.push_back(SCREEN_USER_IMAGE_PICKER);
+
   screen_ids_.clear();
   for (size_t i = 0; i < screen_names_.size(); ++i)
     screen_ids_[screen_names_[i]] = static_cast<Screen>(i);
@@ -634,7 +645,17 @@ void OobeUI::OnCurrentScreenChanged(const std::string& screen) {
   previous_screen_ = current_screen_;
   DCHECK(screen_ids_.count(screen))
       << "Screen should be registered in InitializeScreenMaps()";
+  LOG(ERROR) << "OnCurrentScreenChanged:" << screen;
   Screen new_screen = screen_ids_[screen];
+
+  bool should_dim =
+      std::find(dim_overlay_screen_ids_.begin(), dim_overlay_screen_ids_.end(),
+                new_screen) != dim_overlay_screen_ids_.end();
+  ash::ScreenDimmer* screen_dimmer = ash::ScreenDimmer::GetForContainer(
+      ash::kShellWindowId_LockScreenContainersContainer);
+  screen_dimmer->set_at_bottom(true);
+  screen_dimmer->SetDimming(should_dim);
+
   FOR_EACH_OBSERVER(Observer,
                     observer_list_,
                     OnCurrentScreenChanged(current_screen_, new_screen));
diff --git a/chrome/browser/ui/webui/chromeos/login/oobe_ui.h b/chrome/browser/ui/webui/chromeos/login/oobe_ui.h
index 72e8568..d710683 100644
--- a/chrome/browser/ui/webui/chromeos/login/oobe_ui.h
+++ b/chrome/browser/ui/webui/chromeos/login/oobe_ui.h
@@ -246,6 +246,8 @@ class OobeUI : public OobeDisplay,
   // Maps screen ids to JS screen names.
   std::vector<std::string> screen_names_;
 
+  std::vector<Screen> dim_overlay_screen_ids_;
+
   // Flag that indicates whether JS part is fully loaded and ready to accept
   // calls.
   bool ready_;