Makes escape cancel a snap operation from the maximize button.

ash/wm/workspace/frame_maximize_button.h

Index: ash/wm/workspace/frame_maximize_button.h
diff --git a/ash/wm/workspace/frame_maximize_button.h b/ash/wm/workspace/frame_maximize_button.h
index 7d95d335e5fd3332b1729a9ec6c4db493b554e1b..7dc9ca341db5a1eed8c6b20b7f3f0be9bfef041c 100644
--- a/ash/wm/workspace/frame_maximize_button.h
+++ b/ash/wm/workspace/frame_maximize_button.h
@@ -34,6 +34,8 @@ class ASH_EXPORT FrameMaximizeButton : public views::ImageButton {
   virtual SkBitmap GetImageToPaint() OVERRIDE;
 
  private:
+  class EscapeEventFilter;
+
   // Where to snap to.
   enum SnapType {
     SNAP_LEFT,
@@ -43,6 +45,13 @@ class ASH_EXPORT FrameMaximizeButton : public views::ImageButton {
     SNAP_NONE
   };
 
+  // Cancels snap behavior.
+  void Cancel();
+
+  // Installs/uninstalls an EventFilter to track when escape is pressed.
+  void InstallEventFilter();
+  void UninstallEventFilter();
+
   // Updates |snap_type_| based on a mouse drag. The parameters are relative to
   // the mouse pressed location.
   void UpdateSnap(int delta_x, int delta_y);
@@ -73,6 +82,8 @@ class ASH_EXPORT FrameMaximizeButton : public views::ImageButton {
   // Current snap type.
   SnapType snap_type_;
 
+  scoped_ptr<EscapeEventFilter> escape_event_filter_;
+
   DISALLOW_COPY_AND_ASSIGN(FrameMaximizeButton);
 };