Refactor monitor_reconfigure to stop using system("xrandr").

resolution_selector.h

Index: resolution_selector.h
diff --git a/resolution_selector.h b/resolution_selector.h
index e2920902020876da559aab372434809235ad867d..54e69bec715d2f681d58212ab2fda4729169d6cb 100644
--- a/resolution_selector.h
+++ b/resolution_selector.h
@@ -20,12 +20,19 @@ class ResolutionSelector {
   // A single mode supported by a device, equivalent to the XRRModeInfo
   // struct.
   struct Mode {
-    Mode(int width, int height, std::string name)
+    Mode(int width, int height, std::string name, int id)
         : width(width),
           height(height),
-          name(name) {
+          name(name),
+          id(id) {
     }
 
+    Mode()
+        : width(0),
+          height(0),
+          name(""),
+          id(0) {
+    }
     // Mode's dimensions.
     int width;
     int height;
@@ -33,6 +40,9 @@ class ResolutionSelector {
     // Mode's name from XRandR.  This uniquely describes the mode and can
     // be used to set the devices's resolution later.
     std::string name;
+
+    // The mode id, used for setting this mode.
+    unsigned id;
   };
 
   // Maximum screen size for the external output at which we assume that
@@ -55,13 +65,13 @@ class ResolutionSelector {
   };
 
   // Find the "best" resolutions for various outputs.
-  // The returned strings contain |name| values from the passed-in modes.
+  // Returns the modes for both screens and the total screen resolution.
   bool FindBestResolutions(
       const std::vector<Mode>& lcd_modes,
       const std::vector<Mode>& external_modes,
-      std::string* lcd_resolution,
-      std::string* external_resolution,
-      std::string* screen_resolution);
+      Mode* lcd_resolution,
+      Mode* external_resolution,
+      Mode* screen_resolution);
 
  private:
   // Find resolutions to use that are reasonably close together.
@@ -73,9 +83,9 @@ class ResolutionSelector {
   bool FindNearestResolutions(
       const std::vector<Mode>& larger_device_modes,
       const std::vector<Mode>& smaller_device_modes,
-      std::string* larger_resolution,
-      std::string* smaller_resolution,
-      std::string* screen_resolution);
+      Mode* larger_resolution,
+      Mode* smaller_resolution,
+      Mode* screen_resolution);
 
   DISALLOW_COPY_AND_ASSIGN(ResolutionSelector);
 };