This adds in the ability for Chrome to generate windows with snapshots of all...

chrome/browser/renderer_host/backing_store_x.cc

 // Copyright (c) 2010 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/renderer_host/backing_store_x.h"
 
 #include <cairo-xlib.h>
 #include <gtk/gtk.h>
 #include <stdlib.h>
 #include <sys/ipc.h>
@@ skipping 308 matching lines @@
     }
   } else {
     // Non-shared memory case just copy the image from the server.
     image = XGetImage(display_, pixmap_,
                       rect.x(), rect.y(), width, height,
                       AllPlanes, ZPixmap);
   }
 
   // TODO(jhawkins): Need to convert the image data if the image bits per pixel
   // is not 32.
+  // Note that this also initializes the output bitmap as opaque.
   if (!output->initialize(width, height, true) ||
       image->bits_per_pixel != 32) {
     if (shared_memory_support_ != x11_util::SHARED_MEMORY_NONE)
       DestroySharedImage(display_, image, &shminfo);
     else
       XDestroyImage(image);
     return false;
   }
 
-  // The X image might have a different row stride, so iterate through it and
-  // copy each row out, only up to the pixels we're actually using.
-  // This code assumes a visual mode where a pixel is represented using
-  // a byte for each component.
+  // The X image might have a different row stride, so iterate through
+  // it and copy each row out, only up to the pixels we're actually
+  // using.  This code assumes a visual mode where a pixel is
+  // represented using a 32-bit unsigned int, with a byte per component.
   SkBitmap bitmap = output->getTopPlatformDevice().accessBitmap(true);
   for (int y = 0; y < height; y++) {
+    const uint32* src_row = reinterpret_cast<uint32*>(
+        &image->data[image->bytes_per_line * y]);
     uint32* dest_row = bitmap.getAddr32(0, y);
-    const char* src_row = &image->data[image->bytes_per_line * y];
-    memcpy(dest_row, src_row, width * 4);
+    for (int x = 0; x < width; ++x, ++dest_row) {
+      // Force alpha to be 0xff, because otherwise it causes rendering problems.
+      *dest_row = src_row[x] | 0xff000000;
+    }
   }
 
   if (shared_memory_support_ != x11_util::SHARED_MEMORY_NONE)
     DestroySharedImage(display_, image, &shminfo);
   else
     XDestroyImage(image);
 
   HISTOGRAM_TIMES("BackingStore.RetrievalFromX",
                   base::TimeTicks::Now() - begin_time);
   return true;
@@ skipping 70 matching lines @@
   cairo_set_source(cr, pattern);
   cairo_pattern_destroy(pattern);
 
   cairo_identity_matrix(cr);
 
   cairo_rectangle(cr, rect.x(), rect.y(), rect.width(), rect.height());
   cairo_fill(cr);
   cairo_destroy(cr);
 }
 #endif