Introduce ash::features::kDisplayAlignmentAssistance

This change introduces a new ash::features to enable indicators when a
user has difficulty moving their mouse between displays and when a user
moves displays around in display layouts.

Continuation of CL: crrev.com/c/2145792

Bug: 1070122
Change-Id: I85c52c42abc03f96600efa3877a758ef0d1cf853
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2158033Reviewed-by: Zentaro Kavanagh <zentaro@chromium.org>
Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Commit-Queue: Bailey Berro <baileyberro@chromium.org>
Auto-Submit: Bailey Berro <baileyberro@chromium.org>
Cr-Commit-Position: refs/heads/master@{#761140}

ash/public/cpp/ash_features.cc

@@ -25,6 +25,9 @@ const base::Feature kCornerShortcuts{"CornerShortcuts",
 const base::Feature kContextualNudges{"ContextualNudges",
                                       base::FEATURE_ENABLED_BY_DEFAULT};
 
+const base::Feature kDisplayAlignAssist{"DisplayAlignAssist",
+                                        base::FEATURE_DISABLED_BY_DEFAULT};
+
 const base::Feature kDisplayChangeModal{"DisplayChangeModal",
                                         base::FEATURE_ENABLED_BY_DEFAULT};
 
@@ -256,6 +259,9 @@ bool IsWebUITabStripTabDragIntegrationEnabled() {
   return base::FeatureList::IsEnabled(kWebUITabStripTabDragIntegration);
 }
 
+bool IsDisplayAlignmentAssistanceEnabled() {
+  return base::FeatureList::IsEnabled(kDisplayAlignAssist);
+}
 namespace {
 
 // The boolean flag indicating if "WebUITabStrip" feature is enabled in Chrome.

ash/public/cpp/ash_features.h

@@ -27,6 +27,9 @@ ASH_PUBLIC_EXPORT extern const base::Feature kContextualNudges;
 // Enables shortcuts on corners of the display.
 ASH_PUBLIC_EXPORT extern const base::Feature kCornerShortcuts;
 
+// Enables indicators to hint where displays are connected.
+ASH_PUBLIC_EXPORT extern const base::Feature kDisplayAlignAssist;
+
 // Enables a modal dialog when resolution or refresh rate change.
 ASH_PUBLIC_EXPORT extern const base::Feature kDisplayChangeModal;
 
@@ -218,6 +221,8 @@ ASH_PUBLIC_EXPORT bool IsDisplayIdentificationEnabled();
 
 ASH_PUBLIC_EXPORT bool IsWebUITabStripTabDragIntegrationEnabled();
 
+ASH_PUBLIC_EXPORT bool IsDisplayAlignmentAssistanceEnabled();
+
 // These two functions are supposed to be temporary functions to set or get
 // whether "WebUITabStrip" feature is enabled from Chrome.
 ASH_PUBLIC_EXPORT void SetWebUITabStripEnabled(bool enabled);