Fix slop region boundary handling.

ui/events/gestures/unified_gesture_detector_enabled.cc

Index: ui/events/gestures/unified_gesture_detector_enabled.cc
diff --git a/ui/events/gestures/unified_gesture_detector_enabled.cc b/ui/events/gestures/unified_gesture_detector_enabled.cc
new file mode 100644
index 0000000000000000000000000000000000000000..409f27737a12a91085080e02b96043b38bca57d7
--- /dev/null
+++ b/ui/events/gestures/unified_gesture_detector_enabled.cc
@@ -0,0 +1,37 @@
+// Copyright 2013 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 "base/command_line.h"
+#include "base/logging.h"
+#include "ui/events/event_switches.h"
+#include "ui/events/gestures/unified_gesture_detector_enabled.h"
+
+namespace ui {
+
+bool IsUnifiedGestureDetectorEnabled() {
+  const bool kUseUnifiedGestureDetectorByDefault = true;
+
+  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
+  const std::string unified_gd_enabled_switch =
+      command_line.HasSwitch(switches::kUnifiedGestureDetector) ?
+      command_line.GetSwitchValueASCII(switches::kUnifiedGestureDetector) :
+      switches::kUnifiedGestureDetectorAuto;
+
+  if (unified_gd_enabled_switch.empty() ||
+      unified_gd_enabled_switch == switches::kUnifiedGestureDetectorEnabled) {
+    return true;
+  } else if (unified_gd_enabled_switch ==

[jdduke (slow), 2014/06/10 16:01:23]

Nit: No need for else if / else with preceding returns.  You could probably just
make the "== ...Disabled" check implicit, removing it and instead checking "!=
...Disabled" at the end for the LOG(ERROR) case, then have the final statement
be "return false".

[tdresser, 2014/06/10 16:41:14]

Cleaned up the if / else stuff.
I think the explicit check is easier to follow - I'll change it if you're really
convinced it's superior.

+                 switches::kUnifiedGestureDetectorDisabled) {
+    return false;
+  } else if (unified_gd_enabled_switch ==
+             switches::kUnifiedGestureDetectorAuto) {
+    return kUseUnifiedGestureDetectorByDefault;
+  } else {
+    LOG(ERROR) << "Invalid --unified-gesture-detector option: "
+               << unified_gd_enabled_switch;
+    return false;
+  }
+}
+
+}  // namespace ui