Fix some gcc 4.4 issues when compiling with toolkit_views.

views/controls/button/custom_button.cc

Index: views/controls/button/custom_button.cc
diff --git a/views/controls/button/custom_button.cc b/views/controls/button/custom_button.cc
index 69ac8401d548752c462b28ee18ea530f732117eb..f9a58f639d20e2d0171d82055d4dd3395121ceee 100644
--- a/views/controls/button/custom_button.cc
+++ b/views/controls/button/custom_button.cc
@@ -96,8 +96,8 @@ bool CustomButton::AcceleratorPressed(const Accelerator& accelerator) {
     memset(&gdk_key, 0, sizeof(GdkEventKey));
     gdk_key.type = GDK_KEY_RELEASE;
     gdk_key.keyval = accelerator.GetKeyCode();
-    gdk_key.state = accelerator.IsAltDown() << 3 +
-                    accelerator.IsCtrlDown() << 2 +
+    gdk_key.state = (accelerator.IsAltDown() << 3) +
+                    (accelerator.IsCtrlDown() << 2) +
                     accelerator.IsShiftDown();
     KeyEvent key_event(&gdk_key, false);
 #endif