Remove DocumentMode usage histogram.

chrome/browser/android/feature_utilities.cc

Index: chrome/browser/android/feature_utilities.cc
diff --git a/chrome/browser/android/feature_utilities.cc b/chrome/browser/android/feature_utilities.cc
index 9e52e29deebe46ff36122f21ee1e8472039db7dc..1fa3bb7b8d4e2b4457bd2109a90590d773d347bf 100644
--- a/chrome/browser/android/feature_utilities.cc
+++ b/chrome/browser/android/feature_utilities.cc
@@ -9,7 +9,6 @@
 using base::android::JavaParamRef;
 
 namespace {
-bool document_mode_enabled = false;
 bool custom_tab_visible = false;
 bool is_in_multi_window_mode = false;
 } // namespace
@@ -17,11 +16,6 @@ bool is_in_multi_window_mode = false;
 namespace chrome {
 namespace android {
 
-RunningModeHistogram GetDocumentModeValue() {
-  return document_mode_enabled ? RUNNING_MODE_DOCUMENT_MODE :
-      RUNNING_MODE_TABBED_MODE;
-}
-
 CustomTabsVisibilityHistogram GetCustomTabsVisibleValue() {
   return custom_tab_visible ? VISIBLE_CUSTOM_TAB :
       VISIBLE_CHROME_TAB;
@@ -34,12 +28,6 @@ bool GetIsInMultiWindowModeValue() {
 } // namespace android
 } // namespace chrome
 
-static void SetDocumentModeEnabled(JNIEnv* env,
-                                   const JavaParamRef<jclass>& clazz,
-                                   jboolean enabled) {
-  document_mode_enabled = enabled;
-}
-
 static void SetCustomTabVisible(JNIEnv* env,
                                 const JavaParamRef<jclass>& clazz,
                                 jboolean visible) {