Misc clean-up of TabCaptureApiTests; and re-enable more tests.

chrome/test/data/extensions/api_test/tab_capture/constraints.js

Index: chrome/test/data/extensions/api_test/tab_capture/constraints.js
diff --git a/chrome/test/data/extensions/api_test/tab_capture/constraints.js b/chrome/test/data/extensions/api_test/tab_capture/constraints.js
index ba6ce24017f80f894b64643400fe45a21c01705e..9f652d5729171540f13bd9536566cdfc4991d6d8 100644
--- a/chrome/test/data/extensions/api_test/tab_capture/constraints.js
+++ b/chrome/test/data/extensions/api_test/tab_capture/constraints.js
@@ -20,7 +20,7 @@ chrome.test.runTests([
     });
   },
 
-  function supportsOptionalMediaConstraints() {
+  function rejectsOptionalMediaConstraints() {
     chrome.tabCapture.capture({
       video: true,
       audio: true,
@@ -36,5 +36,31 @@ chrome.test.runTests([
       chrome.test.assertTrue(!stream);
       chrome.test.succeed();
     });
+  },
+
+  function rejectsInvalidConstraints() {
+    chrome.tabCapture.capture({
+      video: true,
+      audio: true,
+      videoConstraints: {
+        mandatory: {
+          notValid: '123'
+        }
+      }
+    }, function(stream) {
+      chrome.test.assertTrue(!stream);
+
+      chrome.tabCapture.capture({

[miu, 2014/11/19 01:15:54]

This is the second test from api_tests_audio.js, which I expanded and cleaned up
further here.

+        audio: true,
+        audioConstraints: {
+          mandatory: {
+            notValid: '123'
+          }
+        }
+      }, function(stream) {
+        chrome.test.assertTrue(!stream);
+        chrome.test.succeed();
+      });
+    });
   }
 ]);