CrOS: Add a flag to allow easy selection of tablet mode.

chrome/browser/about_flags.cc

Index: chrome/browser/about_flags.cc
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 0c03ffd47cdbb79e8029f692995f52ddec7b080c..d8d74669c7af4500ac4daf1f980bce41abf540c6 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -500,6 +500,18 @@ const FeatureEntry::Choice kNtpSwitchToExistingTabChoices[] = {
 };
 #endif  // OS_ANDROID
 
+#if defined(OS_CHROMEOS)
+const FeatureEntry::Choice kForceTabletModeChoices[] = {
+    {IDS_GENERIC_EXPERIMENT_CHOICE_DEFAULT, "", ""},
+    {IDS_FLAGS_FORCE_TABLET_MODE_TOUCHVIEW, switches::kForceTabletMode,
+     switches::kForceTabletModeTouchView},
+    {IDS_FLAGS_FORCE_TABLET_MODE_CLAMSHELL, switches::kForceTabletMode,
+     switches::kForceTabletModeClamshell},
+    {IDS_FLAGS_FORCE_TABLET_MODE_AUTO, switches::kForceTabletMode,
+     switches::kForceTabletModeAuto},
+};
+#endif  // OS_CHROMEOS
+
 #if defined(OS_ANDROID)
 const FeatureEntry::FeatureParam
     kContentSuggestionsCategoryOrderFeatureVariationGeneral[] = {
@@ -2349,6 +2361,12 @@ const FeatureEntry kFeatureEntries[] = {
          kSpeculativeResourcePrefetchingFeatureVariations,
          "SpeculativeResourcePrefetchingValidation")},
 
+#if defined(OS_CHROMEOS)
+    {"force-tablet-mode", IDS_FLAGS_FORCE_TABLET_MODE_NAME,
+     IDS_FLAGS_FORCE_TABLET_MODE_DESCRIPTION, kOsCrOS,
+     MULTI_VALUE_TYPE(kForceTabletModeChoices)},
+#endif  // OS_CHROMEOS
+
     // NOTE: Adding new command-line switches requires adding corresponding
     // entries to enum "LoginCustomFlags" in histograms.xml. See note in
     // histograms.xml and don't forget to run AboutFlagsHistogramTest unit test.