Add WindowManager to about:gpu page on Linux/X11

ui/base/x/x11_util.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_BASE_X_X11_UTIL_H_
 #define UI_BASE_X_X11_UTIL_H_
 
 // This file declares utility functions for X11 (Linux only).
 //
 // These functions do not require the Xlib headers to be included (which is why
@@ skipping 244 matching lines @@
   WM_METACITY,
   WM_MUFFIN,
   WM_MUTTER,
   WM_OPENBOX,
   WM_XFWM4,
 };
 // Attempts to guess the window maager. Returns WM_UNKNOWN if we can't
 // determine it for one reason or another.
 UI_BASE_EXPORT WindowManagerName GuessWindowManager();
 
+// The same as GuessWindowManager(), but returns the raw string.  If we
+// can't determine it, return "Unknown".
+UI_BASE_EXPORT std::string GuessWindowManagerName();
+
 // Enable the default X error handlers. These will log the error and abort
 // the process if called. Use SetX11ErrorHandlers() from x11_util_internal.h
 // to set your own error handlers.
 UI_BASE_EXPORT void SetDefaultX11ErrorHandlers();
 
 // Returns true if a given window is in full-screen mode.
 UI_BASE_EXPORT bool IsX11WindowFullScreen(XID window);
 
 // Returns true if the window manager supports the given hint.
 UI_BASE_EXPORT bool WmSupportsHint(XAtom atom);
@@ skipping 77 matching lines @@
 UI_BASE_EXPORT void ResetXCursorCache();
 
 // Returns the cached XcursorImage for |cursor|.
 UI_BASE_EXPORT const XcursorImage* GetCachedXcursorImage(::Cursor cursor);
 
 }  // namespace test
 
 }  // namespace ui
 
 #endif  // UI_BASE_X_X11_UTIL_H_