<webview> Clarify allowtransparency documentation.

chrome/common/extensions/docs/templates/intros/webview_tag.html

Index: chrome/common/extensions/docs/templates/intros/webview_tag.html
diff --git a/chrome/common/extensions/docs/templates/intros/webview_tag.html b/chrome/common/extensions/docs/templates/intros/webview_tag.html
index 74742b4a5a481f150e639a5c242eb49a39e3fbc8..2345c1156fa85c363883af9682cbf1a3190c61a5 100644
--- a/chrome/common/extensions/docs/templates/intros/webview_tag.html
+++ b/chrome/common/extensions/docs/templates/intros/webview_tag.html
@@ -120,11 +120,14 @@ app that the <code>webview</code> is embedded in).
 
 <h3 id="allowtransparency">allowtransparency</h3>
   <div class="summary">
-    <pre>&lt;webview id="foo" src="http://www.google.com/" style="width:640px; height:480px" <strong>allowtransparency="on"</strong>>&lt;/webview></pre>
+    <pre>&lt;webview id="foo" src="http://www.google.com/" style="width:640px; height:480px" <strong>allowtransparency</strong>>&lt;/webview></pre>
   </div>
   <div class="description">
     <p>
-    If "on", transparent elements within the <code>webview</code> will be shown as transparent. Without <code>allowtransparency</code> enabled, there will be no transparency within the <code>webview</code>, even if elements exist that are specified as transparent.
+    If present, portions of the embedder could be visible through the <code>webview</code>, where the contents are transparent. Without <code>allowtransparency</code> enabled, no part of the embedder will be shown through the <code>webview</code>, even if elements exist that are specified as transparent.
+    </p>
+    <p>
+    This does not affect transparency within the contents of the <code>webview</code> itself.
     </p>
   </div>