Fix up reload button to not flicker, and simplify implementation.

chrome/browser/ui/cocoa/image_button_cell.h

Index: chrome/browser/ui/cocoa/image_button_cell.h
diff --git a/chrome/browser/ui/cocoa/image_button_cell.h b/chrome/browser/ui/cocoa/image_button_cell.h
index c049294457448237eeb0e30831daa7d2a74bee01..f7ca608a3763cb0eee923d77421cba4c2c603d3f 100644
--- a/chrome/browser/ui/cocoa/image_button_cell.h
+++ b/chrome/browser/ui/cocoa/image_button_cell.h
@@ -21,6 +21,13 @@ enum ButtonState {
 
 } // namespace ImageButtonCell
 
+@protocol ImageButton
+@optional
+// Sent from an ImageButtonCell to it's view when the mouse enters or exits the
+// cell.
+- (void)mouseInsideStateDidChange:(BOOL)isInside;
+@end
+
 // A button cell that can disable a different image for each possible button
 // state. Images are specified by image IDs.
 @interface ImageButtonCell : NSButtonCell {