Disable window dragging from top and tab dragging in tablet mode...

if mohnstrudel (#webui-tab-strip) is enabled.

Mohnstrudel (#webui-tab-strip) will enabled on krane from M81 and other
boards from M82. So window dragging from top and tab dragging will be
disabled on krane from M81 and other boards from M82.

Bug: 1041928
Change-Id: I1b071a190a669374906ff6ec16493dbec879d2d1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2031668Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Xiaoqian Dai <xdai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#737046}

ash/public/cpp/ash_features.cc

@@ -231,5 +231,20 @@ bool IsDisplayChangeModalEnabled() {
   return base::FeatureList::IsEnabled(kDisplayChangeModal);
 }
 
+namespace {
+
+// The boolean flag indicating if "WebUITabStrip" feature is enabled in Chrome.
+bool g_webui_tab_strip_enabled = false;
+
+}  // namespace
+
+void SetWebUITabStripEnabled(bool enabled) {
+  g_webui_tab_strip_enabled = enabled;
+}
+
+bool IsWebUITabStripEnabled() {
+  return g_webui_tab_strip_enabled;
+}
+
 }  // namespace features
 }  // namespace ash

ash/public/cpp/ash_features.h

@@ -191,6 +191,11 @@ ASH_PUBLIC_EXPORT bool IsHideShelfControlsInTabletModeEnabled();
 
 ASH_PUBLIC_EXPORT bool IsDisplayChangeModalEnabled();
 
+// These two functions are supposed to be temporary functions to set or get
+// whether "WebUITabStrip" feature is enabled from Chrome.
+ASH_PUBLIC_EXPORT void SetWebUITabStripEnabled(bool enabled);
+ASH_PUBLIC_EXPORT bool IsWebUITabStripEnabled();
+
 }  // namespace features
 }  // namespace ash
 

ash/wm/workspace/workspace_window_resizer.cc

@@ -11,6 +11,7 @@
 #include <vector>
 
 #include "ash/public/cpp/app_types.h"
+#include "ash/public/cpp/ash_features.h"
 #include "ash/public/cpp/shell_window_ids.h"
 #include "ash/root_window_controller.h"
 #include "ash/screen_util.h"
@@ -59,6 +60,12 @@ std::unique_ptr<WindowResizer> CreateWindowResizerForTabletMode(
     const gfx::PointF& point_in_parent,
     int window_component,
     ::wm::WindowMoveSource source) {
+  // Window dragging from top and tab dragging are disabled if "WebUITabStrip"
+  // feature is enabled. "WebUITabStrip" will be enabled on 81 for Krane and on
+  // 82 for all other boards.
+  if (features::IsWebUITabStripEnabled())
+    return nullptr;
+
   WindowState* window_state = WindowState::Get(window);
   // Only maximized/fullscreen/snapped window can be dragged from the top of
   // the screen.

chrome/browser/ui/ash/ash_shell_init.cc

@@ -6,11 +6,13 @@
 
 #include <utility>
 
+#include "ash/public/cpp/ash_features.h"
 #include "ash/shell.h"
 #include "ash/shell_init_params.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/ui/ash/chrome_shell_delegate.h"
 #include "chrome/browser/ui/ash/keyboard/chrome_keyboard_ui_factory.h"
+#include "chrome/browser/ui/ui_features.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "content/public/browser/context_factory.h"
 #include "ui/aura/window_tree_host.h"
@@ -37,6 +39,10 @@ void CreateShell() {
 AshShellInit::AshShellInit() {
   CreateShell();
   ash::Shell::GetPrimaryRootWindow()->GetHost()->Show();
+
+  // Push browser feature flags to ash.
+  ash::features::SetWebUITabStripEnabled(
+      base::FeatureList::IsEnabled(features::kWebUITabStrip));
 }
 
 AshShellInit::~AshShellInit() {