Fix NewApi Lint errors for TabsTest.

NewApi warnings were suppressed accidentally and an AssertionError
constructor that requires API 19 was used. The NewApi warnings are back,
so this fix avoids using the AssertionError, and throws the exceptions
as they are.

This is an accidental leftover from the previous fixes, and is blocking
the CL that removes the NewApi error suppression.

Bug: 805509,803484
Change-Id: Ib2cc11c3ffdcfc50a4618d98d016ab52e0f1f624
Reviewed-on: https://chromium-review.googlesource.com/891578Reviewed-by: David Trainor <dtrainor@chromium.org>
Commit-Queue: Troy Hildebrandt <thildebr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532538}

chrome/android/javatests/src/org/chromium/chrome/browser/TabsTest.java

@@ -652,7 +652,7 @@ public class TabsTest {
      */
     @Test
     @FlakyTest
-    public void testOpenManyTabsInBursts() throws InterruptedException {
+    public void testOpenManyTabsInBursts() throws InterruptedException, TimeoutException {
         mTestServer = EmbeddedTestServer.createAndStartServer(InstrumentationRegistry.getContext());
         final int burstSize = 5;
         final String url = mTestServer.getURL(TEST_PAGE_FILE_PATH);
@@ -674,7 +674,7 @@ public class TabsTest {
      */
     @Test
     @FlakyTest(message = "crbug.com/223110")
-    public void testOpenManyTabsAtOnce10() throws InterruptedException {
+    public void testOpenManyTabsAtOnce10() throws InterruptedException, TimeoutException {
         openAndVerifyManyTestTabs(10);
     }
 
@@ -682,7 +682,8 @@ public class TabsTest {
      * Verify that we can open a large number of tabs all at once and that each
      * tab loads when selected.
      */
-    private void openAndVerifyManyTestTabs(final int num) throws InterruptedException {
+    private void openAndVerifyManyTestTabs(final int num)
+            throws InterruptedException, TimeoutException {
         mTestServer = EmbeddedTestServer.createAndStartServer(InstrumentationRegistry.getContext());
         final String url = mTestServer.getURL(TEST_PAGE_FILE_PATH);
         int startCount = mActivityTestRule.getActivity().getCurrentTabModel().getCount();
@@ -1943,7 +1944,7 @@ public class TabsTest {
      * @param numTabs The number of tabs to open.
      */
     private void loadUrlInManyNewTabs(final String url, final int numTabs)
-            throws InterruptedException {
+            throws InterruptedException, TimeoutException {
         final CallbackHelper[] pageLoadedCallbacks = new CallbackHelper[numTabs];
         final int[] tabIds = new int[numTabs];
         for (int i = 0; i < numTabs; ++i) {
@@ -1978,12 +1979,7 @@ public class TabsTest {
                     TabModelUtils.setIndex(tabModel, tabModel.indexOf(tab));
                 }
             });
-            try {
-                pageLoadedCallbacks[i].waitForCallback(0);
-            } catch (TimeoutException e) {
-                throw new AssertionError(
-                        "PAGE_LOAD_FINISHED was not received for tabId=" + tabIds[i], e);
-            }
+            pageLoadedCallbacks[i].waitForCallback(0);
         }
     }
 }