[Mac] Reimplement HoverButton and HoverImageButton using NSButton.state.

ui/base/cocoa/hover_image_button.mm

Index: ui/base/cocoa/hover_image_button.mm
diff --git a/ui/base/cocoa/hover_image_button.mm b/ui/base/cocoa/hover_image_button.mm
index 3cdf509122e261023cab1bb464dc87d68214c2ef..0e433164977c9cacbd5a2990b92bd9928e7005a8 100644
--- a/ui/base/cocoa/hover_image_button.mm
+++ b/ui/base/cocoa/hover_image_button.mm
@@ -6,28 +6,27 @@
 
 @implementation HoverImageButton
 
-- (void)drawRect:(NSRect)rect {
-  if (hoverState_ == kHoverStateMouseDown && pressedImage_) {
-    [super setImage:pressedImage_.get()];
-  } else if (hoverState_ == kHoverStateMouseOver && hoverImage_) {
-    [super setImage:hoverImage_.get()];
-  } else {
-    [super setImage:defaultImage_.get()];
-  }
-
-  [super drawRect:rect];
+- (void)setIsMouseInside:(BOOL)isInside {
+  if (isInside && hoverImage_)
+    [self setImage:hoverImage_];
+  else
+    [self setImage:defaultImage_];
+
+  [super setIsMouseInside:isInside];
 }
 
 - (void)setDefaultImage:(NSImage*)image {
   defaultImage_.reset([image retain]);
+  [self checkImageState];
 }
 
 - (void)setHoverImage:(NSImage*)image {
   hoverImage_.reset([image retain]);
+  [self checkImageState];
 }
 
 - (void)setPressedImage:(NSImage*)image {
-  pressedImage_.reset([image retain]);
+  [self setAlternateImage:image];
 }
 
 @end