cros: Change tab discard code to use CopyStateFrom, add tests

* Use NavigationController::CopyStateFrom() to preserve the back/forward history of discarded tabs.
* Extend browser_test to ensure back/forward history is preserved.
* Change browser_test to wait for NAV_ENTRY_COMMITTED notification, which eliminates a source of flake in the test.
* Wrote small unit test for NavigationController::CopyStateFrom() - strangely it didn't have one.
* Added scaffolding and TODO for using SuddenTerminationAllowed() in the scoring system for discard.

BUG=121453
TEST=content_unittests NavigationControllerTest and browser_tests OomPriorityManagerTest


Review URL: http://codereview.chromium.org/10052017

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@131931 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 35 insertions, 0 deletions

diff --git a/content/browser/web_contents/navigation_controller_impl_unittest.cc b/content/browser/web_contents/navigation_controller_impl_unittest.cc
index 33ca391..3812a38 100644
--- a/content/browser/web_contents/navigation_controller_impl_unittest.cc
+++ b/content/browser/web_contents/navigation_controller_impl_unittest.cc
@@ -2064,6 +2064,41 @@ TEST_F(NavigationControllerTest, SubframeWhilePending) {
   EXPECT_EQ(url2, controller.GetActiveEntry()->GetURL());
 }
 
+// Test CopyStateFrom with 2 urls, the first selected and nothing in the target.
+TEST_F(NavigationControllerTest, CopyStateFrom) {
+  NavigationControllerImpl& controller = controller_impl();
+  const GURL url1("http://foo1");
+  const GURL url2("http://foo2");
+
+  NavigateAndCommit(url1);
+  NavigateAndCommit(url2);
+  controller.GoBack();
+  contents()->CommitPendingNavigation();
+
+  scoped_ptr<TestWebContents> other_contents(
+      static_cast<TestWebContents*>(CreateTestWebContents()));
+  NavigationControllerImpl& other_controller =
+      other_contents->GetControllerImpl();
+  other_controller.CopyStateFrom(controller);
+
+  // other_controller should now contain 2 urls.
+  ASSERT_EQ(2, other_controller.GetEntryCount());
+  // We should be looking at the first one.
+  ASSERT_EQ(0, other_controller.GetCurrentEntryIndex());
+
+  EXPECT_EQ(url1, other_controller.GetEntryAtIndex(0)->GetURL());
+  EXPECT_EQ(0, other_controller.GetEntryAtIndex(0)->GetPageID());
+  EXPECT_EQ(url2, other_controller.GetEntryAtIndex(1)->GetURL());
+  // This is a different site than url1, so the IDs start again at 0.
+  EXPECT_EQ(0, other_controller.GetEntryAtIndex(1)->GetPageID());
+
+  // The max page ID map should be copied over and updated with the max page ID
+  // from the current tab.
+  SiteInstance* instance1 =
+      GetSiteInstanceFromEntry(other_controller.GetEntryAtIndex(0));
+  EXPECT_EQ(0, other_contents->GetMaxPageIDForSiteInstance(instance1));
+}
+
 // Tests CopyStateFromAndPrune with 2 urls in source, 1 in dest.
 TEST_F(NavigationControllerTest, CopyStateFromAndPrune) {
   NavigationControllerImpl& controller = controller_impl();