Fix ThumbnailGenerator on Windows.

app/surface/transport_dib.h

 // 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.
 
 #ifndef APP_SURFACE_TRANSPORT_DIB_H_
 #define APP_SURFACE_TRANSPORT_DIB_H_
 #pragma once
 
 #include "base/basictypes.h"
 
@@ skipping 106 matching lines @@
   //
   // The sequence number is used to uniquely identify the transport DIB. It
   // should be unique for all transport DIBs ever created in the same
   // renderer.
   static TransportDIB* Create(size_t size, uint32 sequence_num);
 
   // Map the referenced transport DIB.  The caller owns the returned object.
   // Returns NULL on failure.
   static TransportDIB* Map(Handle transport_dib);
 
+  // Create a new |TransportDIB| with a handle to the shared memory. This
+  // always returns a valid pointer. The DIB is not mapped.
+  static TransportDIB* CreateWithHandle(Handle handle);
+
   // Returns true if the handle is valid.
   static bool is_valid(Handle dib);
 
   // Returns a canvas using the memory of this TransportDIB. The returned
   // pointer will be owned by the caller. The bitmap will be of the given size,
   // which should fit inside this memory.
   //
+  // On POSIX, this |TransportDIB| will be mapped if not already. On Windows,
+  // this |TransportDIB| will NOT be mapped and should not be mapped prior,
+  // because PlatformCanvas will map the file internally.
+  //
   // Will return NULL on allocation failure. This could be because the image
   // is too large to map into the current process' address space.
   skia::PlatformCanvas* GetPlatformCanvas(int w, int h);
 
-  // Return a pointer to the shared memory
+  // Map the DIB into the current process if it is not already. This is used to
+  // map a DIB that has already been created. Returns true if the DIB is mapped.
+  bool Map();
+
+  // Return a pointer to the shared memory.
   void* memory() const;
 
   // Return the maximum size of the shared memory. This is not the amount of
   // data which is valid, you have to know that via other means, this is simply
   // the maximum amount that /could/ be valid.
   size_t size() const { return size_; }
 
   // Return the identifier which can be used to refer to this shared memory
   // on the wire.
   Id id() const;
@@ skipping 19 matching lines @@
   void* address_;  // mapped address
   XSharedMemoryId x_shm_;  // X id for the shared segment
   Display* display_;  // connection to the X server
 #endif
   size_t size_;  // length, in bytes
 
   DISALLOW_COPY_AND_ASSIGN(TransportDIB);
 };
 
 #endif  // APP_SURFACE_TRANSPORT_DIB_H_