Add Get/SetDisplayLayout to chrome.system.display extension API

extensions/browser/api/system_display/display_info_provider.h

Index: extensions/browser/api/system_display/display_info_provider.h
diff --git a/extensions/browser/api/system_display/display_info_provider.h b/extensions/browser/api/system_display/display_info_provider.h
index 6715ba8f40d0ee149c4475fbcfa9445ca868af53..54e44abf7f56e5844d674b887ec863a65bc6a6c5 100644
--- a/extensions/browser/api/system_display/display_info_provider.h
+++ b/extensions/browser/api/system_display/display_info_provider.h
@@ -20,16 +20,18 @@ namespace extensions {
 
 namespace api {
 namespace system_display {
+struct DisplayLayout;
 struct DisplayProperties;
 struct DisplayUnitInfo;
 struct Insets;
 }
 }
 
-typedef std::vector<api::system_display::DisplayUnitInfo> DisplayUnitInfoList;
-
 class DisplayInfoProvider {
  public:
+  using DisplayUnitInfoList = std::vector<api::system_display::DisplayUnitInfo>;
+  using DisplayLayoutList = std::vector<api::system_display::DisplayLayout>;
+
   virtual ~DisplayInfoProvider();
 
   // Returns a pointer to DisplayInfoProvider or NULL if Create()
@@ -47,13 +49,20 @@ class DisplayInfoProvider {
                        const api::system_display::DisplayProperties& info,
                        std::string* error) = 0;
 
-  // Enable the unified desktop feature.
+  // Implements SetDisplayLayout methods. See system_display.idl. Returns
+  // false if the layout input is invalid.
+  virtual bool SetDisplayLayout(const DisplayLayoutList& layouts);
+
+  // Enables the unified desktop feature.
   virtual void EnableUnifiedDesktop(bool enable);
 
-  // Get display information.
+  // Gets display information.
   virtual DisplayUnitInfoList GetAllDisplaysInfo();
 
-  // Implement overscan calbiration methods. See system_display.idl. These
+  // Gets display layout information.
+  virtual DisplayLayoutList GetDisplayLayout();
+
+  // Implements overscan calbiration methods. See system_display.idl. These
   // return false if |id| is invalid.
   virtual bool OverscanCalibrationStart(const std::string& id);
   virtual bool OverscanCalibrationAdjust(