Small optimization for <webview> tooltips.

content/browser/browser_plugin/browser_plugin_guest.cc

Index: content/browser/browser_plugin/browser_plugin_guest.cc
diff --git a/content/browser/browser_plugin/browser_plugin_guest.cc b/content/browser/browser_plugin/browser_plugin_guest.cc
index 45da41a73db7332d8461139454d9c35ad67b1573..9fed4123a706293d76cf6b54cdf25905ba66425c 100644
--- a/content/browser/browser_plugin/browser_plugin_guest.cc
+++ b/content/browser/browser_plugin/browser_plugin_guest.cc
@@ -129,6 +129,10 @@ void BrowserPluginGuest::SetFocus(RenderWidgetHost* rwh, bool focused) {
 }
 
 void BrowserPluginGuest::SetTooltipText(const base::string16& tooltip_text) {
+  if (tooltip_text == current_tooltip_text_)
+    return;
+  current_tooltip_text_ = tooltip_text;
+
   SendMessageToEmbedder(new BrowserPluginMsg_SetTooltipText(
       browser_plugin_instance_id_, tooltip_text));
 }