Disable system suspend while downloading files on win32.

If the system goes into power-save sleep mode while downloading files,
the download fails. So, prevent sleep mode until the download finishes.

This patch introduces a new RAII class to request that the system's
power-save mode be disabled - PowerSaveBlocker.
This is only implemented for win32; other platforms are stubbed out.

This only partially implements bug 25420 it only attempts to handle the
downloading case.

Patch by Bryan Donlan <bdonlan@gmail.com>

BUG=25420
TEST=Download a large file with the system sleep timeout set to a short interval.
Review URL: http://codereview.chromium.org/287017

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@29873 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 21 insertions, 0 deletions

diff --git a/chrome/browser/power_save_blocker_win.cc b/chrome/browser/power_save_blocker_win.cc
new file mode 100644
index 0000000..f7d3d8c
--- /dev/null
+++ b/chrome/browser/power_save_blocker_win.cc
@@ -0,0 +1,21 @@
+// Copyright (c) 2009 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/power_save_blocker.h"
+
+#include <windows.h>
+
+#include "chrome/browser/chrome_thread.h"
+
+// Runs on UI thread only.
+void PowerSaveBlocker::ApplyBlock(bool blocking) {
+  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::UI));
+
+  DWORD flags = ES_CONTINUOUS;
+
+  if (blocking)
+    flags |= ES_SYSTEM_REQUIRED;
+
+  SetThreadExecutionState(flags);
+}