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

chrome/browser/ui/cocoa/image_button_cell.mm

Index: chrome/browser/ui/cocoa/image_button_cell.mm
diff --git a/chrome/browser/ui/cocoa/image_button_cell.mm b/chrome/browser/ui/cocoa/image_button_cell.mm
index fe6dcb9f6504a0c61637f461ecffefc33ac21212..bb81227123cacb13f1fc97b15415dde73a82832f 100644
--- a/chrome/browser/ui/cocoa/image_button_cell.mm
+++ b/chrome/browser/ui/cocoa/image_button_cell.mm
@@ -138,10 +138,25 @@ const CGFloat kImageNoFocusAlpha = 0.65;
 - (void)setIsMouseInside:(BOOL)isMouseInside {
   if (isMouseInside_ != isMouseInside) {
     isMouseInside_ = isMouseInside;
-    [[self controlView] setNeedsDisplay:YES];
+    NSView<ImageButton>* control =
+        static_cast<NSView<ImageButton>*>([self controlView]);
+    if ([control respondsToSelector:@selector(mouseInsideStateDidChange:)]) {
+      [control mouseInsideStateDidChange:isMouseInside];
+    }
+    [control setNeedsDisplay:YES];
   }
 }
 
+- (void)setShowsBorderOnlyWhileMouseInside:(BOOL)show {
+  VLOG_IF(1, !show) << "setShowsBorderOnlyWhileMouseInside:NO ignored";
+}
+
+- (BOOL)showsBorderOnlyWhileMouseInside {
+  // Always returns YES so that buttons always get mouse tracking even when
+  // disabled. The reload button (and possibly others) depend on this.
+  return YES;
+}
+
 - (void)mouseEntered:(NSEvent*)theEvent {
   [self setIsMouseInside:YES];
 }