Fixed flaky test.

It appears to be an issue with the "textarea" not always getting focus
before the "commitText()" call is made.  A tiny delay to let everything
settle seems to fix the issue.

BUG=477632
TBR=bcwhite

Review URL: https://codereview.chromium.org/1104293007

Cr-Commit-Position: refs/heads/master@{#327577}

content/public/android/javatests/src/org/chromium/content/browser/input/ImeTest.java

@@ -324,17 +324,14 @@ public class ImeTest extends ContentShellTestBase {
         assertWaitForKeyboardStatus(true);
     }
 
-    /*
     @SmallTest
     @Feature({"TextInput", "Main"})
-    http://crbug.com/477632
-    */
-    @DisabledTest
     public void testFinishComposingText() throws Throwable {
         DOMUtils.focusNode(mWebContents, "input_radio");
         assertWaitForKeyboardStatus(false);
         DOMUtils.focusNode(mWebContents, "textarea");
         assertWaitForKeyboardStatus(true);
+        Thread.sleep(50);
 
         mConnection = (TestAdapterInputConnection) getAdapterInputConnection();
         waitAndVerifyEditableCallback(mConnection.mImeUpdateQueue, 0, "", 0, 0, -1, -1);