Introduce XGetImage() for GrabWindowSnapshot() in ChromeOS.

chrome/browser/ui/window_snapshot/window_snapshot_aura.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 "chrome/browser/ui/window_snapshot/window_snapshot.h"
 
 #include "base/logging.h"
 #include "third_party/skia/include/core/SkBitmap.h"
+#include "ui/aura/root_window.h"
 #include "ui/aura/window.h"
 #include "ui/compositor/compositor.h"
 #include "ui/compositor/dip_util.h"
 #include "ui/compositor/layer.h"
 #include "ui/gfx/codec/png_codec.h"
 #include "ui/gfx/rect.h"
 
 namespace browser {
 
 bool GrabWindowSnapshot(gfx::NativeWindow window,
                         std::vector<unsigned char>* png_representation,
                         const gfx::Rect& snapshot_bounds) {
+#if defined(OS_LINUX)
+  // We use XGetImage() for Linux/ChromeOS for performance reasons.
+  // See crbug.com/122720
+  if (window->GetRootWindow()->GrabSnapshot(
+          snapshot_bounds, png_representation))
+    return true;
+#endif  // OS_LINUX
+
   ui::Compositor* compositor = window->layer()->GetCompositor();
 
   gfx::Rect read_pixels_bounds = snapshot_bounds;
 
   // When not in compact mode we must take into account the window's position on
   // the desktop.
   read_pixels_bounds.set_origin(
       snapshot_bounds.origin().Add(window->bounds().origin()));
   gfx::Rect read_pixels_bounds_in_pixel =
       ui::ConvertRectToPixel(window->layer(), read_pixels_bounds);
@@ skipping 11 matching lines @@
 
   gfx::PNGCodec::Encode(pixels, gfx::PNGCodec::FORMAT_BGRA,
                         read_pixels_bounds_in_pixel.size(),
                         bitmap.rowBytes(), true,
                         std::vector<gfx::PNGCodec::Comment>(),
                         png_representation);
   return true;
 }
 
 }  // namespace browser