Widen the keyboard detection logic on Windows 8 touch devices and detect slate...

Widen the keyboard detection logic on Windows 8 touch devices and detect slate mode to force OSK on.

Changes in this patch as below:-

1. We now check if the device is docked and avoid displaying the OSK in this case.

2. Check the auto rotation state of the device via the
   GetAutoRotationState API. If auto rotation is disabled
   or not supported we can safely assume that a keyboard
   is present on the system.

3. Allow ACPI\* device names in the keyboard device name matching code.

4. Detect if the device is in slate mode, i.e. the keyboard is flipped. We need to display
   the OSK in this case.

BUG=335735

Review URL: https://codereview.chromium.org/988883003

Cr-Commit-Position: refs/heads/master@{#319826}

base/win/win_util.cc

@@ -70,6 +70,53 @@ bool IsKeyboardPresentOnSlate() {
     return true;
   }
 
+  // If the device is docked, the user is treating the device as a PC.
+  if (GetSystemMetrics(SM_SYSTEMDOCKED) != 0)
+    return true;
+
+  // To determine whether a keyboard is present on the device, we do the
+  // following:-
+  // 1. Check whether the device supports auto rotation. If it does then
+  //    it possibly supports flipping from laptop to slate mode. If it
+  //    does not support auto rotation, then we assume it is a desktop
+  //    or a normal laptop and assume that there is a keyboard.
+
+  // 2. If the device supports auto rotation, then we get its platform role
+  //    and check the system metric SM_CONVERTIBLESLATEMODE to see if it is
+  //    being used in slate mode. If yes then we return false here to ensure
+  //    that the OSK is displayed.
+
+  // 3. If step 1 and 2 fail then we check attached keyboards and return true
+  //    if we find ACPI\* or HID\VID* keyboards.
+
+  typedef BOOL (WINAPI* GetAutoRotationState)(PAR_STATE state);
+
+  GetAutoRotationState get_rotation_state =
+      reinterpret_cast<GetAutoRotationState>(::GetProcAddress(
+          GetModuleHandle(L"user32.dll"), "GetAutoRotationState"));
+
+  if (get_rotation_state) {
+    AR_STATE auto_rotation_state = AR_ENABLED;
+    get_rotation_state(&auto_rotation_state);
+    if ((auto_rotation_state & AR_NOSENSOR) ||
+        (auto_rotation_state & AR_NOT_SUPPORTED)) {
+      // If there is no auto rotation sensor or rotation is not supported in
+      // the current configuration, then we can assume that this is a desktop
+      // or a traditional laptop.
+      return true;
+    }
+  }
+
+  // Check if the device is being used as a laptop or a tablet. This can be
+  // checked by first checking the role of the device and then the
+  // corresponding system metric (SM_CONVERTIBLESLATEMODE). If it is being used
+  // as a tablet then we want the OSK to show up.
+  POWER_PLATFORM_ROLE role = PowerDeterminePlatformRole();
+
+  if (((role == PlatformRoleMobile) || (role == PlatformRoleSlate)) &&
+       (GetSystemMetrics(SM_CONVERTIBLESLATEMODE) == 0))
+    return false;
+
   const GUID KEYBOARD_CLASS_GUID =
       { 0x4D36E96B, 0xE325,  0x11CE,
           { 0xBF, 0xC1, 0x08, 0x00, 0x2B, 0xE1, 0x03, 0x18 } };
@@ -97,10 +144,9 @@ bool IsKeyboardPresentOnSlate() {
                                         MAX_DEVICE_ID_LEN,
                                         0);
     if (status == CR_SUCCESS) {
-      // To reduce the scope of the hack we only look for PNP, MSF and HID
-      // keyboards.
-      if (StartsWith(device_id, L"ACPI\\PNP", false) ||
-          StartsWith(device_id, L"ACPI\\MSF", false) ||
+      // To reduce the scope of the hack we only look for ACPI and HID\\VID
+      // prefixes in the keyboard device ids.
+      if (StartsWith(device_id, L"ACPI", false) ||
           StartsWith(device_id, L"HID\\VID", false)) {
         keyboard_count++;
       }