Update tabCapture API docs with browser action info.

BUG=230911

Review URL: https://chromiumcodereview.appspot.com/14107010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@195178 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/extensions/api/tab_capture/tab_capture_api.cc

@@ -41,7 +41,8 @@ const char kFindingTabError[] = "Error finding tab to capture.";
 const char kNoAudioOrVideo[] = "Capture failed. No audio or video requested.";
 const char kPermissionError[] = "Tab Capture API flag is not enabled.";
 const char kGrantError[] =
-    "Capture of this tab must be granted by clicking on the extension icon.";
+    "Extension has not been invoked for the current page (see activeTab "
+    "permission). Chrome pages cannot be captured.";
 
 // Keys/values for media stream constraints.
 const char kMediaStreamSource[] = "chromeMediaSource";

chrome/common/extensions/api/tab_capture.idl

@@ -47,7 +47,10 @@ namespace tabCapture {
 
   interface Functions {
     // Captures the visible area of the currently active tab.
-    // Extensions must have the "tabCapture" permission to use this method.
+    // This method can only be used on the currently active page after the
+    // extension has been <em>invoked</em>, similar to the way that
+    // <a href="activeTab.html">activeTab</a> works.
+    // Note that Chrome internal pages cannot be captured.
     // |options| : Configures the returned media stream.
     // |callback| : Callback with either the stream returned or null.
     static void capture(CaptureOptions options,

chrome/test/data/extensions/api_test/tab_capture/experimental/active_tab_permission_test.js

@@ -28,7 +28,8 @@ var afterGrantPermission = function(msg) {
 var afterOpenTab = function(msg) {
   chrome.tabCapture.capture({audio: true, video: true}, function(stream) {
     chrome.test.assertLastError(
-      'Capture of this tab must be granted by clicking on the extension icon.');
+      'Extension has not been invoked for the current page (see activeTab ' +
+      'permission). Chrome pages cannot be captured.');
     chrome.test.assertTrue(!stream);
 
     chrome.test.sendMessage('ready2', afterGrantPermission);