x11: Use opaque window for dnd without composite.

content/browser/gpu/gpu_internals_ui.cc

 // 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.
 
 #include "content/browser/gpu/gpu_internals_ui.h"
 
 #include <stddef.h>
 
 #include <memory>
 #include <string>
@@ skipping 200 matching lines @@
                                              ui::GuessWindowManagerName()));
   {
     std::unique_ptr<base::Environment> env(base::Environment::Create());
     std::string value;
     const char kXDGCurrentDesktop[] = "XDG_CURRENT_DESKTOP";
     if (env->GetVar(kXDGCurrentDesktop, &value))
       basic_info->Append(NewDescriptionValuePair(kXDGCurrentDesktop, value));
     const char kGDMSession[] = "GDMSESSION";
     if (env->GetVar(kGDMSession, &value))
       basic_info->Append(NewDescriptionValuePair(kGDMSession, value));
-    const char* const kAtomsToCache[] = {
-        "_NET_WM_CM_S0",
-        NULL
-    };
-    ui::X11AtomCache atom_cache(gfx::GetXDisplay(), kAtomsToCache);
-    std::string compositing_manager = XGetSelectionOwner(
-        gfx::GetXDisplay(),
-        atom_cache.GetAtom("_NET_WM_CM_S0")) != None ? "Yes" : "No";
-    basic_info->Append(
-        NewDescriptionValuePair("Compositing manager", compositing_manager));
+    basic_info->Append(NewDescriptionValuePair(
+        "Compositing manager",
+        ui::IsCompositingManagerPresent() ? "Yes" : "No"));
   }
 #endif
   std::string direct_rendering = gpu_info.direct_rendering ? "Yes" : "No";
   basic_info->Append(
       NewDescriptionValuePair("Direct rendering", direct_rendering));
 
   std::string reset_strategy =
       base::StringPrintf("0x%04x", gpu_info.gl_reset_notification_strategy);
   basic_info->Append(NewDescriptionValuePair(
       "Reset notification strategy", reset_strategy));
@@ skipping 319 matching lines @@
     : WebUIController(web_ui) {
   web_ui->AddMessageHandler(base::MakeUnique<GpuMessageHandler>());
 
   // Set up the chrome://gpu/ source.
   BrowserContext* browser_context =
       web_ui->GetWebContents()->GetBrowserContext();
   WebUIDataSource::Add(browser_context, CreateGpuHTMLSource());
 }
 
 }  // namespace content