Revert "Temporarily disable in-browser thumbnailing on Win and Mac."

This reverts commit 4cc7f1d.

Now the cause of http://crbug.com/130916 was identified and fixed, I'll re-enable in-browser thumbnailer on Win and Mac.

BUG=130916,120003
TEST=Manual

Review URL: https://chromiumcodereview.appspot.com/10554018

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@142776 0039d316-1c4b-4281-b951-d872f2087c98

chrome/common/thumbnail_support.cc

@@ -16,9 +16,15 @@ bool ShouldEnableInBrowserThumbnailing() {
           switches::kDisableInBrowserThumbnailing))
     return false;
 
-#if defined(OS_CHROMEOS)
+#if defined(OS_WIN)
+  // Disables in-browser thumbnailing on Windows XP where not supported yet.
+  if (base::win::GetVersion() < base::win::VERSION_VISTA)
+    return false;
   return true;
-#else
+#elif defined(OS_LINUX) && !defined(USE_AURA)
+  // Disables in-browser thumbnailing on non-Aura Linux where not supported yet.
   return false;
+#else
+  return true;
 #endif
 }