Use immersive for apps only in fullscreen state.

Looks like I misunderstood the comment when I refactored.

BUG=843856
TEST=covered by unittest

Change-Id: I6fb735472af25e833ef2a40f99bd0a26867da3fb
Reviewed-on: https://chromium-review.googlesource.com/1107214Reviewed-by: Ben Wells <benwells@chromium.org>
Commit-Queue: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568743}

chrome/browser/ui/views/apps/chrome_native_app_window_views_aura_ash.cc

@@ -584,8 +584,8 @@ bool ChromeNativeAppWindowViewsAuraAsh::ShouldEnableImmersiveMode() const {
   if (app_window()->IsForcedFullscreen())
     return false;
 
-  // Always use immersive mode in a public session.
-  if (profiles::IsPublicSession())
+  // Always use immersive mode in a public session in fullscreen state.
+  if (profiles::IsPublicSession() && IsFullscreen())
     return true;
 
   // Always use immersive mode when fullscreen is set by the OS.

chrome/browser/ui/views/apps/chrome_native_app_window_views_aura_ash.h

@@ -127,6 +127,8 @@ class ChromeNativeAppWindowViewsAuraAsh
                            ImmersiveModeFullscreenRestoreType);
   FRIEND_TEST_ALL_PREFIXES(ChromeNativeAppWindowViewsAuraAshBrowserTest,
                            NoImmersiveModeWhenForcedFullscreen);
+  FRIEND_TEST_ALL_PREFIXES(ChromeNativeAppWindowViewsAuraAshBrowserTest,
+                           PublicSessionImmersiveMode);
   FRIEND_TEST_ALL_PREFIXES(ChromeNativeAppWindowViewsAuraAshInteractiveTest,
                            NoImmersiveOrBubbleOutsidePublicSessionWindow);
   FRIEND_TEST_ALL_PREFIXES(ChromeNativeAppWindowViewsAuraAshInteractiveTest,

chrome/browser/ui/views/apps/chrome_native_app_window_views_aura_ash_browsertest.cc

@@ -12,6 +12,8 @@
 #include "ui/base/ui_base_types.h"
 #include "ui/wm/core/window_util.h"
 
+#include "chromeos/login/login_state.h"
+
 class ChromeNativeAppWindowViewsAuraAshBrowserTest
     : public extensions::PlatformAppBrowserTest {
  public:
@@ -145,3 +147,24 @@ IN_PROC_BROWSER_TEST_F(ChromeNativeAppWindowViewsAuraAshBrowserTest,
   tablet_mode_controller->FlushForTesting();
   EXPECT_FALSE(window->immersive_fullscreen_controller_->IsEnabled());
 }
+
+// Make sure a normal window is not in immersive mode, and uses
+// immersive in fullscreen.
+IN_PROC_BROWSER_TEST_F(ChromeNativeAppWindowViewsAuraAshBrowserTest,
+                       PublicSessionImmersiveMode) {
+  chromeos::LoginState::Get()->SetLoggedInState(
+      chromeos::LoginState::LOGGED_IN_ACTIVE,
+      chromeos::LoginState::LOGGED_IN_USER_PUBLIC_ACCOUNT);
+
+  extensions::AppWindow* app_window = CreateTestAppWindow("{}");
+  auto* window = static_cast<ChromeNativeAppWindowViewsAuraAsh*>(
+      GetNativeAppWindowForAppWindow(app_window));
+  ASSERT_TRUE(window != nullptr);
+  ASSERT_TRUE(window->immersive_fullscreen_controller_.get() != nullptr);
+  EXPECT_FALSE(window->immersive_fullscreen_controller_->IsEnabled());
+
+  app_window->SetFullscreen(extensions::AppWindow::FULLSCREEN_TYPE_HTML_API,
+                            true);
+
+  EXPECT_TRUE(window->immersive_fullscreen_controller_->IsEnabled());
+}