cocoa browser: add accessible tooltip for security state

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

Index: chrome/browser/ui/cocoa/location_bar/security_state_bubble_decoration.mm
diff --git a/chrome/browser/ui/cocoa/location_bar/security_state_bubble_decoration.mm b/chrome/browser/ui/cocoa/location_bar/security_state_bubble_decoration.mm
index 6a5f597d93f95d3b18b216849c78c280b97d22ab..1003d097eac21a49bef800e89128b9e4af8947d7 100644
--- a/chrome/browser/ui/cocoa/location_bar/security_state_bubble_decoration.mm
+++ b/chrome/browser/ui/cocoa/location_bar/security_state_bubble_decoration.mm
@@ -11,9 +11,11 @@
 #import "chrome/browser/ui/cocoa/location_bar/location_bar_view_mac.h"
 #import "chrome/browser/ui/cocoa/location_bar/location_icon_decoration.h"
 #import "chrome/browser/ui/cocoa/themed_window.h"
+#include "chrome/grit/generated_resources.h"
 #include "chrome/grit/theme_resources.h"
 #include "skia/ext/skia_utils_mac.h"
 #import "ui/base/cocoa/nsview_additions.h"
+#include "ui/base/l10n/l10n_util_mac.h"
 #include "ui/base/material_design/material_design_controller.h"
 #include "ui/gfx/animation/tween.h"
 #include "ui/gfx/color_palette.h"
@@ -290,6 +292,11 @@
                      NSMaxY(image_rect) - kPageInfoBubblePointYOffset);
 }
 
+NSString* SecurityStateBubbleDecoration::GetToolTip() {
+  return [NSString stringWithFormat:@"%@. %@", full_label_.get(),
+                   l10n_util::GetNSStringWithFixup(IDS_TOOLTIP_LOCATION_ICON)];
+}
+
 //////////////////////////////////////////////////////////////////
 // SecurityStateBubbleDecoration::BubbleDecoration: