Query the current window with chrome.tabs.query using -1.

chrome/common/extensions/docs/windows.html

Index: chrome/common/extensions/docs/windows.html
diff --git a/chrome/common/extensions/docs/windows.html b/chrome/common/extensions/docs/windows.html
index 1e7feacf98c44429bd2db2bb822a55f2fb4c89a8..889364a4e997c79762e5d0997d89de898535008a 100644
--- a/chrome/common/extensions/docs/windows.html
+++ b/chrome/common/extensions/docs/windows.html
@@ -330,6 +330,8 @@
             <ol>
               <li>
                 <a href="#property-WINDOW_ID_NONE">WINDOW_ID_NONE</a>
+              </li><li>
+                <a href="#property-WINDOW_ID_CURRENT">WINDOW_ID_CURRENT</a>
               </li>
             </ol>
           </li>
@@ -562,6 +564,80 @@ For other examples and for help in viewing the source code, see
           </dd>
 
         </div>
+            </div><div>
+              <a name="property-WINDOW_ID_CURRENT"></a>
+              <h4>WINDOW_ID_CURRENT</h4>
+              <div class="summary">
+                <!-- Note: intentionally longer 80 columns -->
+                <span>chrome.windows.</span><span>WINDOW_ID_CURRENT</span>
+              </div>
+              <div>
+          <dt>
+            <var>WINDOW_ID_CURRENT</var>
+              <em>
+
+                <!-- TYPE -->
+                <div style="display:inline">
+                  (
+                    <span class="optional" style="display: none; ">optional</span>
+                    <span class="enum" style="display: none; ">enumerated</span>
+                    <span id="typeTemplate">
+                      <span style="display: none; ">
+                        <a> Type</a>
+                      </span>
+                      <span>
+                        <span style="display: none; ">
+                          array of <span><span></span></span>
+                        </span>
+                        <span>integer</span>
+                        <span style="display: none; "></span>
+                      </span>
+                    </span>
+                  )
+                </div>
+
+              </em>
+          </dt>
+          <dd class="todo" style="display: none; ">
+            Undocumented.
+          </dd>
+          <dd>The windowId value that represents the <a href="windows.html#current-window">current window</a>.</dd>
+          <dd style="display: none; ">
+            This parameter was added in version
+            <b><span></span></b>.
+            You must omit this parameter in earlier versions,
+            and you may omit it in any version.  If you require this
+            parameter, the manifest key
+            <a href="manifest.html#minimum_chrome_version">minimum_chrome_version</a>
+            can ensure that your extension won't be run in an earlier browser version.
+          </dd>
+
+          <!-- OBJECT PROPERTIES -->
+          <dd style="display: none; ">
+            <dl>
+              <div>
+                <div>
+                </div>
+              </div>
+            </dl>
+          </dd>
+
+          <!-- OBJECT METHODS -->
+          <dd style="display: none; ">
+            <div></div>
+          </dd>
+
+          <!-- OBJECT EVENT FIELDS -->
+          <dd style="display: none; ">
+            <div></div>
+          </dd>
+
+          <!-- FUNCTION PARAMETERS -->
+          <dd style="display: none; ">
+            <div></div>
+          </dd>
+
+        </div>
             </div>
 
           </div> <!-- /apiGroup -->