Long press menu (shift+f6) to toggle spoken feedback.

ash/magnifier/magnifier_key_scroller.h

Index: ash/magnifier/magnifier_key_scroller.h
diff --git a/ash/magnifier/magnifier_key_scroller.h b/ash/magnifier/magnifier_key_scroller.h
index 4f9f19efb68367a96cbc9147ff1a6947c3611fd3..173d6249f2f647b7b77936134fcea71c108a6c7e 100644
--- a/ash/magnifier/magnifier_key_scroller.h
+++ b/ash/magnifier/magnifier_key_scroller.h
@@ -5,6 +5,7 @@
 #ifndef ASH_MAGNIFIER_MAGNIFIER_KEY_SCROLLER_H_
 #define ASH_MAGNIFIER_MAGNIFIER_KEY_SCROLLER_H_
 
+#include "ash/accelerators/key_hold_detector.h"
 #include "ash/ash_export.h"
 #include "ui/events/event_handler.h"
 
@@ -14,18 +15,12 @@ class KeyEvent;
 
 namespace ash {
 
-// This class implements the press and hold key-bindings (shift-arrow keys)
-// to control magnified screen.
-class ASH_EXPORT MagnifierKeyScroller : public ui::EventHandler {
+// A KeyHoldDetector delegate to control control magnified screen.
+class ASH_EXPORT MagnifierKeyScroller : public KeyHoldDetector::Delegate {
  public:
   static bool IsEnabled();
   static void SetEnabled(bool enabled);
-
-  MagnifierKeyScroller();
-  virtual ~MagnifierKeyScroller();
-
-  // ui::EventHandler overrides:
-  virtual void OnKeyEvent(ui::KeyEvent* key_event) OVERRIDE;
+  static ui::EventHandler* CreateHandler();

[xiyuan, 2014/02/14 01:50:21]

Same here. Document the ownership of the returned object and maybe add
WARN_UNUSED_RESULT.

 
   // A scoped object to enable and disable the magnifier accelerator for test.
   class ScopedEnablerForTest {
@@ -42,22 +37,14 @@ class ASH_EXPORT MagnifierKeyScroller : public ui::EventHandler {
   };
 
  private:
-  // A state to keep track of one click and click and hold operation.
-  //
-  // One click:
-  // INITIAL --(first press)--> PRESSED --(release)--> INITIAL[SEND PRESS]
-  //
-  // Click and hold:
-  // INITIAL --(first press)--> PRESSED --(press)-->
-  //   HOLD[scroll] --(press)--> HOLD[scroll] --(release)-->
-  //   INITIAL[stop scroll]
-  enum State {
-    INITIAL,
-    PRESSED,
-    HOLD
-  };
+  // KeyHoldDetector overrides:
+  virtual bool ShouldProcessEvent(const ui::KeyEvent* event) const OVERRIDE;
+  virtual bool IsStartEvent(const ui::KeyEvent* event) const OVERRIDE;
+  virtual void OnKeyHold(const ui::KeyEvent* event) OVERRIDE;
+  virtual void OnKeyUnhold(const ui::KeyEvent* event) OVERRIDE;
 
-  State state_;
+  MagnifierKeyScroller();
+  virtual ~MagnifierKeyScroller();
 
   DISALLOW_COPY_AND_ASSIGN(MagnifierKeyScroller);
 };