Use active window if on current workspace for fullscreen mode.

ash/wm/workspace/workspace_layout_manager.cc

Index: ash/wm/workspace/workspace_layout_manager.cc
diff --git a/ash/wm/workspace/workspace_layout_manager.cc b/ash/wm/workspace/workspace_layout_manager.cc
index 4e79c6e83d114f84213addf40e982c06bb4bbf6b..d717cdcde544b98ce815aa46130a4eed4a73951b 100644
--- a/ash/wm/workspace/workspace_layout_manager.cc
+++ b/ash/wm/workspace/workspace_layout_manager.cc
@@ -218,7 +218,6 @@ void WorkspaceLayoutManager::OnWindowPropertyChanged(Window* window,
 
 void WorkspaceLayoutManager::OnWindowStackingChanged(aura::Window* window) {
   UpdateShelfVisibility();
-  UpdateFullscreenState();

[oshima, 2014/02/14 20:09:30]

I think this one should stay here. Technically it's possible to move the
fullscreen window to topmost on another display without changing activation ,
right?

[flackr, 2014/02/14 20:15:01]

Correct, but this calls OnWindowRemovedFromLayout on the current layout manager
and OnWindowAddedToLayout on the new layout manager.

 }
 
 void WorkspaceLayoutManager::OnWindowDestroying(aura::Window* window) {
@@ -247,6 +246,7 @@ void WorkspaceLayoutManager::OnWindowActivated(aura::Window* gained_active,
     window_state->Unminimize();
     DCHECK(!window_state->IsMinimized());
   }
+  UpdateFullscreenState();

[oshima, 2014/02/14 17:24:26]

All layout managers are notified for activation change, aren't they?

I think this is one thing I overlooked when I merged BaseLayoutManager and right
fix is to observe only events that needs. Better short term fix may be

if (!shelf_)
  return;

in UpdateFullscreenState(). WDYT?

[flackr, 2014/02/14 20:00:02]

Yes, since it's a ShellObserver notification, that's why I had to make the
change in UpdateFullscreenState.
That sounds nicer in the meantime, done. Thanks!

 }
 
 //////////////////////////////////////////////////////////////////////////////
@@ -425,8 +425,16 @@ void WorkspaceLayoutManager::UpdateShelfVisibility() {
 }
 
 void WorkspaceLayoutManager::UpdateFullscreenState() {
-  bool is_fullscreen = GetRootWindowController(
-      window_->GetRootWindow())->GetWindowForFullscreenMode() != NULL;
+  const aura::Window* fullscreen_window = GetRootWindowController(
+      window_->GetRootWindow())->GetWindowForFullscreenMode();
+  // TODO(flackr): The fullscreen state is currently tracked per workspace
+  // but the shell notification implies a per root window state. Currently
+  // only windows in the default workspace container will go fullscreen so
+  // this should correctly track the root window fullscreen state but this
+  // should really be tracked by the RootWindowController since technically
+  // any container could get a fullscreen window.
+  bool is_fullscreen = fullscreen_window &&
+                       window_->Contains(fullscreen_window);
   if (is_fullscreen != is_fullscreen_) {
     ash::Shell::GetInstance()->NotifyFullscreenStateChange(
         is_fullscreen, window_->GetRootWindow());