a11y: use decoration tooltip for location bar decoration view a11y title

chrome/browser/ui/cocoa/location_bar/location_bar_decoration.mm

Index: chrome/browser/ui/cocoa/location_bar/location_bar_decoration.mm
diff --git a/chrome/browser/ui/cocoa/location_bar/location_bar_decoration.mm b/chrome/browser/ui/cocoa/location_bar/location_bar_decoration.mm
index 3c7a0a85fb39382a97def596098632150ac67507..0c010f056896273eb9daaff64c76eaf34fe05859 100644
--- a/chrome/browser/ui/cocoa/location_bar/location_bar_decoration.mm
+++ b/chrome/browser/ui/cocoa/location_bar/location_bar_decoration.mm
@@ -34,6 +34,7 @@ const CGFloat kMaterialDividerIncognitoGrayScale = 1.0;
 - (BOOL)acceptsFirstResponder;
 - (void)drawRect:(NSRect)dirtyRect;
 - (NSView*)hitTest:(NSPoint)aPoint;
+- (NSString*)accessibilityLabel;
 
 // This method is called when this DecorationAccessibilityView is activated.
 - (void)actionDidHappen;
@@ -75,6 +76,10 @@ const CGFloat kMaterialDividerIncognitoGrayScale = 1.0;
   owner_->OnAccessibilityViewAction();
 }
 
+- (NSString*)accessibilityLabel {
+  return owner_->GetToolTip();
+}
+
 @end
 
 const CGFloat LocationBarDecoration::kOmittedWidth = 0.0;