Add shortcut keys to ui scaling

ash/accelerators/accelerator_controller.cc

Index: ash/accelerators/accelerator_controller.cc
diff --git a/ash/accelerators/accelerator_controller.cc b/ash/accelerators/accelerator_controller.cc
index 62b33ba7be86fc164ade89b5eb0ae96de3906c55..b751a8a579f98fffaf9c077b7423c4235d79b38f 100644
--- a/ash/accelerators/accelerator_controller.cc
+++ b/ash/accelerators/accelerator_controller.cc
@@ -154,7 +154,7 @@ bool HandleRotateActiveWindow() {
   return true;
 }
 
-const DisplayInfo::Rotation GetNextRotation(DisplayInfo::Rotation current) {
+DisplayInfo::Rotation GetNextRotation(DisplayInfo::Rotation current) {
   switch (current) {
     case DisplayInfo::ROTATE_0:
       return DisplayInfo::ROTATE_90;
@@ -169,13 +169,38 @@ const DisplayInfo::Rotation GetNextRotation(DisplayInfo::Rotation current) {
   return DisplayInfo::ROTATE_0;
 }
 
+float GetNextScale(float scale, int next) {
+  // These scales are equivalent to 1024, 1280, 1600 and 1920 pixel width
+  // respectively on 2560 pixel width 2x density display.
+  static const float kScales[] = {0.8f, 1.0f, 1.25f, 1.5f};
+  static const int size = arraysize(kScales);

[James Cook, 2013/03/14 17:50:43]

size -> kScalesSize, or inline the use of arraysize(kScales)

[oshima, 2013/03/14 19:56:15]

Done.

+  int index = std::distance(kScales, std::find(kScales, kScales + size, scale));
+  // Fallback to 1.0f if the |scale| wasn't in the list.
+  index = index == size ? 1 : index + next;
+  return kScales[std::max(std::min(3, index), 0)];

[James Cook, 2013/03/14 17:50:43]

Use size-1 instead of 3.

[oshima, 2013/03/14 19:56:15]

Done.

+}
+
+bool HandleScaleUI(bool up) {
+  // UI Scaling is effective only on internal display.
+  int64 display_id = gfx::Display::InternalDisplayId();
+#if defined(OS_CHROMEOS)
+  // On linux desktop, allow ui scaling on the first dislpay.
+  if (!base::chromeos::IsRunningOnChromeOS())
+    display_id = Shell::GetInstance()->display_manager()->first_display_id();
+#endif
+  const gfx::Display& display = Shell::GetInstance()->display_manager()->
+      GetDisplayForId(display_id);
+  const DisplayInfo& display_info = Shell::GetInstance()->display_manager()->
+      GetDisplayInfo(display);
+  Shell::GetInstance()->display_manager()->SetDisplayUIScale(
+      display.id(), GetNextScale(display_info.ui_scale(), up ? 1 : -1));
+  return true;
+}
+
 // Rotates the screen.
 bool HandleRotateScreen() {
-  aura::Window* active_window = wm::GetActiveWindow();
-  if (!active_window)
-    return false;
-  const gfx::Display& display =
-      Shell::GetScreen()->GetDisplayNearestWindow(active_window);
+  gfx::Point point = Shell::GetScreen()->GetCursorScreenPoint();
+  gfx::Display display = Shell::GetScreen()->GetDisplayNearestPoint(point);
   const DisplayInfo& display_info =
       Shell::GetInstance()->display_manager()->GetDisplayInfo(display);
   Shell::GetInstance()->display_manager()->SetDisplayRotation(
@@ -756,6 +781,10 @@ bool AcceleratorController::PerformAction(int action,
       }
       break;
     }
+    case SCALE_UI_UP:
+      return HandleScaleUI(true /* up */);
+    case SCALE_UI_DOWN:
+      return HandleScaleUI(false /* down */);
     case ROTATE_WINDOW:
       return HandleRotateActiveWindow();
     case ROTATE_SCREEN:
@@ -765,7 +794,7 @@ bool AcceleratorController::PerformAction(int action,
     case TOGGLE_ROOT_WINDOW_FULL_SCREEN:
       return HandleToggleRootWindowFullScreen();
     case DISPLAY_TOGGLE_SCALE:
-      internal::DisplayManager::ToggleDisplayScale();
+      internal::DisplayManager::ToggleDisplayScaleFactor();
       return true;
     case MAGNIFY_SCREEN_ZOOM_IN:
       return HandleMagnifyScreen(1);