Add scroll and gesture message filters for UIPI Flash.

chrome/common/chrome_content_client.cc

Index: chrome/common/chrome_content_client.cc
===================================================================
--- chrome/common/chrome_content_client.cc	(revision 96778)
+++ chrome/common/chrome_content_client.cc	(working copy)
@@ -252,6 +252,13 @@
   ::CloseHandle(process);
   return true;
 }
+
+// Must be dynamically loaded to avoid startup failures on Win XP.
+typedef BOOL (WINAPI *ChangeWindowMessageFilterFunction)(
+    UINT message,
+    DWORD flag);
+ChangeWindowMessageFilterFunction g_ChangeWindowMessageFilter;
+
 #endif  // OS_WIN
 
 }  // namespace
@@ -362,6 +369,18 @@
     policy->SetJobLevel(sandbox::JOB_UNPROTECTED, 0);
     policy->SetTokenLevel(sandbox::USER_RESTRICTED_SAME_ACCESS,
                           sandbox::USER_INTERACTIVE);
+    // Allow the Flash plugin to forward some messages back to Chrome.
+    if (base::win::GetVersion() == base::win::VERSION_VISTA) {
+      if (!g_ChangeWindowMessageFilter) {
+        g_ChangeWindowMessageFilter =
+            reinterpret_cast<ChangeWindowMessageFilterFunction>(
+                ::GetProcAddress(::GetModuleHandle(L"user32.dll"),
+                                 "ChangeWindowMessageFilter"));
+      }
+      // Per-window message filters required on Win7 or later must be added to:
+      // render_widget_host_view_win.cc RenderWidgetHostViewWin::ReparentWindow
+      g_ChangeWindowMessageFilter(WM_MOUSEWHEEL, MSGFLT_ADD);
+    }
     policy->SetIntegrityLevel(sandbox::INTEGRITY_LEVEL_LOW);
   } else {
     // Could not start the broker, use a very weak policy instead.