Aura: Automatically use compact window mode on narrow displays

We default to compact mode on displays with a width of 1366 (ZGB) and narrower.  Only do this when we're not running in a window, to avoid changing the default for Aura developers running on desktop workstations.

BUG=108187
TEST=added unit test

Review URL: http://codereview.chromium.org/9018022

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@115606 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 96 insertions, 4 deletions

diff --git a/ui/aura/root_window.h b/ui/aura/root_window.h
index 0af56b2..b3e91ec 100644
--- a/ui/aura/root_window.h
+++ b/ui/aura/root_window.h
@@ -53,6 +53,9 @@ class AURA_EXPORT RootWindow : public ui::CompositorDelegate,
   static void set_use_fullscreen_host_window(bool use_fullscreen) {
     use_fullscreen_host_window_ = use_fullscreen;
   }
+  static bool use_fullscreen_host_window() {
+    return use_fullscreen_host_window_;
+  }
 
   ui::Compositor* compositor() { return compositor_.get(); }
   gfx::Point last_mouse_location() const { return last_mouse_location_; }
diff --git a/ui/aura_shell/shell.cc b/ui/aura_shell/shell.cc
index de891c8..87c772e 100644
--- a/ui/aura_shell/shell.cc
+++ b/ui/aura_shell/shell.cc
@@ -38,6 +38,8 @@
 #include "ui/aura_shell/workspace_controller.h"
 #include "ui/gfx/compositor/layer.h"
 #include "ui/gfx/compositor/layer_animator.h"
+#include "ui/gfx/screen.h"
+#include "ui/gfx/size.h"
 #include "ui/views/widget/native_widget_aura.h"
 #include "ui/views/widget/widget.h"
 
@@ -47,6 +49,11 @@ namespace {
 
 using views::Widget;
 
+// Screen width at or below which we automatically start in compact window mode,
+// in pixels. Should be at least 1366 pixels, the resolution of ChromeOS ZGB
+// device displays, as we traditionally used a single window on those devices.
+const int kCompactWindowModeWidthThreshold = 1366;
+
 // Creates each of the special window containers that holds windows of various
 // types in the shell UI. They are added to |containers| from back to front in
 // the z-index.
@@ -176,6 +183,16 @@ void Shell::DeleteInstance() {
 }
 
 void Shell::Init() {
+  // On small screens we automatically enable --aura-window-mode=compact if the
+  // user has not explicitly set a window mode flag. This must happen before
+  // we create containers or layout managers.
+  gfx::Size monitor_size = gfx::Screen::GetPrimaryMonitorSize();
+  CommandLine* command_line = CommandLine::ForCurrentProcess();
+  if (DefaultToCompactWindowMode(monitor_size, command_line)) {
+    command_line->AppendSwitchASCII(switches::kAuraWindowMode,
+                                    switches::kAuraWindowModeCompact);
+  }
+
   aura::RootWindow* root_window = aura::RootWindow::GetInstance();
   root_window->SetCursor(aura::kCursorPointer);
 
@@ -194,7 +211,6 @@ void Shell::Init() {
 
   InitLayoutManagers(root_window);
 
-  CommandLine* command_line = CommandLine::ForCurrentProcess();
   if (!command_line->HasSwitch(switches::kAuraNoShadows))
     shadow_controller_.reset(new internal::ShadowController());
 
@@ -214,6 +230,26 @@ void Shell::Init() {
   drag_drop_controller_.reset(new internal::DragDropController);
 }
 
+bool Shell::DefaultToCompactWindowMode(const gfx::Size& monitor_size,
+                                       CommandLine* command_line) const {
+  // Developers often run the Aura shell in a window on their desktop.
+  // Don't mess with their window mode.
+  if (!aura::RootWindow::use_fullscreen_host_window())
+    return false;
+
+  // If user set the flag, don't override their desired behavior.
+  if (command_line->HasSwitch(switches::kAuraWindowMode))
+    return false;
+
+  // If the screen is wide enough, we prefer multiple draggable windows.
+  // We explicitly don't care about height, since users don't generally stack
+  // browser windows vertically.
+  if (monitor_size.width() > kCompactWindowModeWidthThreshold)
+    return false;
+
+  return true;
+}
+
 void Shell::InitLayoutManagers(aura::RootWindow* root_window) {
   internal::RootWindowLayoutManager* root_window_layout =
       new internal::RootWindowLayoutManager(root_window);
diff --git a/ui/aura_shell/shell.h b/ui/aura_shell/shell.h
index 66c88eb..fb971a8 100644
--- a/ui/aura_shell/shell.h
+++ b/ui/aura_shell/shell.h
@@ -10,12 +10,15 @@
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/task.h"
 #include "base/compiler_specific.h"
 #include "base/memory/weak_ptr.h"
 #include "ui/aura_shell/aura_shell_export.h"
 
+class CommandLine;
+
 namespace aura {
 class EventFilter;
 class RootWindow;
@@ -23,6 +26,7 @@ class Window;
 }
 namespace gfx {
 class Rect;
+class Size;
 }
 
 namespace aura_shell {
@@ -93,12 +97,20 @@ class AURA_SHELL_EXPORT Shell {
   }
 
  private:
+  FRIEND_TEST_ALL_PREFIXES(ShellTest, DefaultToCompactWindowMode);
+
   typedef std::pair<aura::Window*, gfx::Rect> WindowAndBoundsPair;
 
   explicit Shell(ShellDelegate* delegate);
   virtual ~Shell();
 
   void Init();
+
+  // Returns true if the |monitor_size| is narrow and the user has not set
+  // an explicit window mode flag on the |command_line|.
+  bool DefaultToCompactWindowMode(const gfx::Size& monitor_size,
+                                  CommandLine* command_line) const;
+
   void InitLayoutManagers(aura::RootWindow* root_window);
 
   // Enables WorkspaceManager.
diff --git a/ui/aura_shell/shell_unittest.cc b/ui/aura_shell/shell_unittest.cc
index f00a3df..0afe720 100644
--- a/ui/aura_shell/shell_unittest.cc
+++ b/ui/aura_shell/shell_unittest.cc
@@ -2,17 +2,20 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include "base/command_line.h"
 #include "base/utf_string_conversions.h"
 #include "ui/aura/test/aura_test_base.h"
+#include "ui/aura/root_window.h"
 #include "ui/aura/window.h"
+#include "ui/aura_shell/aura_shell_switches.h"
 #include "ui/aura_shell/shell.h"
 #include "ui/aura_shell/shell_window_ids.h"
 #include "ui/aura_shell/test/aura_shell_test_base.h"
+#include "ui/gfx/size.h"
 #include "ui/views/widget/widget.h"
 #include "ui/views/widget/widget_delegate.h"
 
 namespace aura_shell {
-namespace test {
 
 namespace {
 
@@ -70,9 +73,23 @@ class ModalWindow : public views::WidgetDelegateView {
   DISALLOW_COPY_AND_ASSIGN(ModalWindow);
 };
 
+// After base::AutoReset<> but via setter and getter.
+class AutoResetUseFullscreenHostWindow {
+ public:
+  AutoResetUseFullscreenHostWindow(bool new_value) {
+    old_value_ = aura::RootWindow::use_fullscreen_host_window();
+    aura::RootWindow::set_use_fullscreen_host_window(new_value);
+  }
+  ~AutoResetUseFullscreenHostWindow() {
+    aura::RootWindow::set_use_fullscreen_host_window(old_value_);
+  }
+ private:
+  bool old_value_;
+};
+
 }  // namespace
 
-class ShellTest : public AuraShellTestBase {
+class ShellTest : public test::AuraShellTestBase {
  public:
   ShellTest() {}
   virtual ~ShellTest() {}
@@ -247,5 +264,29 @@ TEST_F(ShellTest, IsScreenLocked) {
   EXPECT_FALSE(Shell::GetInstance()->IsScreenLocked());
 }
 
-}  // namespace test
+TEST_F(ShellTest, DefaultToCompactWindowMode) {
+  // We only change default window mode with full-screen host windows.
+  AutoResetUseFullscreenHostWindow use_fullscreen_host_window(true);
+
+  // Wide screens use normal window mode.
+  Shell* shell = Shell::GetInstance();
+  gfx::Size monitor_size(1440, 900);
+  CommandLine command_line(CommandLine::NO_PROGRAM);
+  EXPECT_FALSE(shell->DefaultToCompactWindowMode(monitor_size, &command_line));
+
+  // Alex-sized screens need compact mode.
+  monitor_size.SetSize(1280, 800);
+  EXPECT_TRUE(shell->DefaultToCompactWindowMode(monitor_size, &command_line));
+
+  // ZGB-sized screens need compact mode.
+  monitor_size.SetSize(1366, 768);
+  EXPECT_TRUE(shell->DefaultToCompactWindowMode(monitor_size, &command_line));
+
+  // Even for a small screen, the user can force normal mode.
+  monitor_size.SetSize(800, 600);
+  command_line.AppendSwitchASCII(aura_shell::switches::kAuraWindowMode,
+                                 aura_shell::switches::kAuraWindowModeNormal);
+  EXPECT_FALSE(shell->DefaultToCompactWindowMode(monitor_size, &command_line));
+}
+
 }  // namespace aura_shell