Fix ThumbnailGenerator on Windows.

app/surface/transport_dib_win.cc

Index: app/surface/transport_dib_win.cc
diff --git a/app/surface/transport_dib_win.cc b/app/surface/transport_dib_win.cc
index 63506b2ca2d5fa5fb8ca25fbd369f717082291b3..a9ebe697de72b098e716252f7d01951cbd6f8b69 100644
--- a/app/surface/transport_dib_win.cc
+++ b/app/surface/transport_dib_win.cc
@@ -2,9 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include <limits>
 #include <windows.h>
 
+#include <limits>
+
 #include "app/surface/transport_dib.h"

[brettw, 2010/11/09 06:02:40]

Technically this include should be first. Can you move it up to the top while
you're reordering includes?

[kkania, 2012/05/10 19:54:12]

Done.

 #include "base/logging.h"
 #include "base/scoped_ptr.h"
@@ -41,36 +42,55 @@ TransportDIB* TransportDIB::Create(size_t size, uint32 sequence_num) {
 }
 
 // static
-TransportDIB* TransportDIB::Map(TransportDIB::Handle handle) {
-  TransportDIB* dib = new TransportDIB(handle);
-  if (!dib->shared_memory_.Map(0 /* map whole shared memory segment */)) {
-    LOG(ERROR) << "Failed to map transport DIB"
-               << " handle:" << handle
-               << " error:" << GetLastError();
-    delete dib;
+TransportDIB* TransportDIB::Map(Handle handle) {
+  scoped_ptr<TransportDIB> dib(CreateWithHandle(handle));
+  if (!dib->Map())
     return NULL;
-  }
-
-  // There doesn't seem to be any way to find the size of the shared memory
-  // region! GetFileSize indicates that the handle is invalid. Thus, we
-  // conservatively set the size to the maximum and hope that the renderer
-  // isn't about to ask us to read off the end of the array.
-  dib->size_ = std::numeric_limits<size_t>::max();
+  return dib.release();
+}
 
-  return dib;
+// static
+TransportDIB* TransportDIB::CreateWithHandle(Handle handle) {
+  return new TransportDIB(handle);
 }
 
+// static
 bool TransportDIB::is_valid(Handle dib) {
   return dib != NULL;
 }
 
 skia::PlatformCanvas* TransportDIB::GetPlatformCanvas(int w, int h) {
+  // This DIB already mapped the file into this process, but PlatformCanvas
+  // will map it again.
+  DCHECK(!memory()) << "Mapped file twice in the same process.";
+
   scoped_ptr<skia::PlatformCanvas> canvas(new skia::PlatformCanvas);
   if (!canvas->initialize(w, h, true, handle()))
     return NULL;
   return canvas.release();
 }
 
+bool TransportDIB::Map() {
+  if (!is_valid(handle()))
+    return false;
+  if (memory())
+    return true;
+
+  if (!shared_memory_.Map(0 /* map whole shared memory segment */)) {
+    LOG(ERROR) << "Failed to map transport DIB"
+               << " handle:" << shared_memory_.handle()
+               << " error:" << ::GetLastError();
+    return false;
+  }
+
+  // There doesn't seem to be any way to find the size of the shared memory
+  // region! GetFileSize indicates that the handle is invalid. Thus, we
+  // conservatively set the size to the maximum and hope that the renderer
+  // isn't about to ask us to read off the end of the array.
+  size_ = std::numeric_limits<size_t>::max();
+  return true;
+}
+
 void* TransportDIB::memory() const {
   return shared_memory_.memory();
 }
@@ -80,5 +100,5 @@ TransportDIB::Handle TransportDIB::handle() const {
 }
 
 TransportDIB::Id TransportDIB::id() const {
-  return Id(shared_memory_.handle(), sequence_num_);
+  return Id(handle(), sequence_num_);
 }