Make DisplayInfoProvider an interface

chrome/browser/extensions/api/system_display/display_info_provider.cc

Index: chrome/browser/extensions/api/system_display/display_info_provider.cc
diff --git a/chrome/browser/extensions/api/system_display/display_info_provider.cc b/chrome/browser/extensions/api/system_display/display_info_provider.cc
index d57bd15ce0a477cb723337ed4af2b47f92c87ccf..ada4f550099b40fe9019d7c1fb93c4e84fef54c5 100644
--- a/chrome/browser/extensions/api/system_display/display_info_provider.cc
+++ b/chrome/browser/extensions/api/system_display/display_info_provider.cc
@@ -5,6 +5,7 @@
 #include "chrome/browser/extensions/api/system_display/display_info_provider.h"
 
 #include "base/strings/string_number_conversions.h"
+#include "chrome/common/extensions/api/system_display.h"
 #include "ui/gfx/display.h"
 #include "ui/gfx/screen.h"
 
@@ -12,6 +13,9 @@ namespace extensions {
 
 namespace {
 
+// Created on demand and will leak when the process exits.
+DisplayInfoProvider* g_display_info_provider = NULL;
+
 // Converts Rotation enum to integer.
 int RotationToDegrees(gfx::Display::Rotation rotation) {
   switch (rotation) {
@@ -50,21 +54,19 @@ CreateDisplayUnitInfo(const gfx::Display& display, int64 primary_display_id) {
   return unit;
 }
 
-DisplayInfoProvider* g_display_info_provider = NULL;
-
 }  // namespace
 
+DisplayInfoProvider::~DisplayInfoProvider() {
+}
 
-DisplayInfoProvider::DisplayInfoProvider() {}
-
-DisplayInfoProvider::~DisplayInfoProvider() {}
-
+// static
 DisplayInfoProvider* DisplayInfoProvider::Get() {
   if (g_display_info_provider == NULL)
-    g_display_info_provider = new DisplayInfoProvider();
+    g_display_info_provider = DisplayInfoProvider::Create();
   return g_display_info_provider;
 }
 
+// static
 void DisplayInfoProvider::InitializeForTesting(
     DisplayInfoProvider* display_info_provider) {
   DCHECK(display_info_provider);
@@ -86,4 +88,7 @@ DisplayInfo DisplayInfoProvider::GetAllDisplaysInfo() {
   return all_displays;
 }
 
+DisplayInfoProvider::DisplayInfoProvider() {
+}
+
 }  // namespace extensions