cros: Expose new overview ui from flag.

Test: unit_tests AboutFlagsHistogramTest.CheckHistograms
Bug: 782320
Change-Id: I9b75d6e9b9e018b86a8d011653f02887e2a68f1e
Reviewed-on: https://chromium-review.googlesource.com/889920
Commit-Queue: Sammie Quon <sammiequon@chromium.org>
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#533054}

chrome/browser/about_flags.cc

@@ -3685,6 +3685,11 @@ const FeatureEntry kFeatureEntries[] = {
      flag_descriptions::kEnableDisplayZoomSettingName,
      flag_descriptions::kEnableDisplayZoomSettingDescription, kOsCrOS,
      SINGLE_VALUE_TYPE(chromeos::switches::kEnableDisplayZoomSetting)},
+
+    {"ash-enable-new-overview-ui",
+     flag_descriptions::kAshEnableNewOverviewUiName,
+     flag_descriptions::kAshEnableNewOverviewUiDescription, kOsCrOS,
+     SINGLE_VALUE_TYPE(ash::switches::kAshEnableNewOverviewUi)},
 #endif  // defined(OS_CHROMEOS)
 
     // NOTE: Adding a new flag requires adding a corresponding entry to enum

chrome/browser/flag_descriptions.cc

@@ -2933,6 +2933,10 @@ const char kAshEnableMirroredScreenDescription[] =
     "Enable the mirrored screen mode. This mode flips the screen image "
     "horizontally.";
 
+const char kAshEnableNewOverviewUiName[] = "Enable new overview UI.";
+const char kAshEnableNewOverviewUiDescription[] =
+    "Enables the new overview mode UI.";
+
 const char kAshEnablePersistentWindowBoundsName[] =
     "Enable persistent window bounds in multi-displays scenario.";
 const char kAshEnablePersistentWindowBoundsDescription[] =

chrome/browser/flag_descriptions.h

@@ -1809,6 +1809,9 @@ extern const char kAshEnableKeyboardShortcutViewerDescription[];
 extern const char kAshEnableMirroredScreenName[];
 extern const char kAshEnableMirroredScreenDescription[];
 
+extern const char kAshEnableNewOverviewUiName[];
+extern const char kAshEnableNewOverviewUiDescription[];
+
 extern const char kAshEnablePersistentWindowBoundsName[];
 extern const char kAshEnablePersistentWindowBoundsDescription[];
 

tools/metrics/histograms/enums.xml

@@ -26109,6 +26109,7 @@ from previous Chrome versions.
   <int value="67639499" label="stop-loading-in-background:disabled"/>
   <int value="70878462" label="WebAssembly:disabled"/>
   <int value="73929836" label="VrBrowsingInCustomTab:enabled"/>
+  <int value="75237697" label="ash-enable-new-overview-ui"/>
   <int value="75747474" label="disable-webview-signin-flow"/>
   <int value="78998551" label="disable-hosted-app-shim-creation"/>
   <int value="79094339" label="VrLaunchIntents:enabled"/>