Extend ErrorPageTestCase with back-forward and reload navigation tests.

Added the following test cases:
 - testReloadPageAfterServerIsDown
 - testGoForwardAfterServerIsDownAndReload
 - testGoBackFromErrorPage

Bug: 725241
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I6a872e6691c66ff6facd100cdb90607488738ff6
Reviewed-on: https://chromium-review.googlesource.com/1043074Reviewed-by: Danyao Wang <danyao@chromium.org>
Commit-Queue: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#556082}

ios/chrome/browser/web/error_page_egtest.mm

@@ -11,6 +11,7 @@
 #import "ios/chrome/test/earl_grey/chrome_earl_grey.h"
 #import "ios/chrome/test/earl_grey/chrome_test_case.h"
 #include "ios/testing/embedded_test_server_handlers.h"
+#include "net/test/embedded_test_server/default_handlers.h"
 #include "net/test/embedded_test_server/http_request.h"
 #include "net/test/embedded_test_server/http_response.h"
 #include "net/test/embedded_test_server/request_handler_util.h"
@@ -61,12 +62,13 @@ NSString* GetErrorMessage() {
   self.testServer->RegisterRequestHandler(
       base::BindRepeating(&net::test_server::HandlePrefixedRequest, "/iframe",
                           base::BindRepeating(&testing::HandleIFrame)));
+  RegisterDefaultHandlers(self.testServer);
 
   GREYAssertTrue(self.testServer->Start(), @"Test server failed to start.");
 }
 
 // Loads the URL which fails to load, then sucessfully reloads the page.
-- (void)testReload {
+- (void)testReloadErrorPage {
   // No response leads to ERR_INTERNET_DISCONNECTED error.
   self.serverRespondsWithContent = NO;
   [ChromeEarlGrey loadURL:self.testServer->GetURL("/echo-query?foo")];
@@ -78,6 +80,65 @@ NSString* GetErrorMessage() {
   [ChromeEarlGrey waitForWebViewContainingText:"foo"];
 }
 
+// Sucessfully loads the page, stops the server and reloads the page.
+- (void)testReloadPageAfterServerIsDown {
+  // Sucessfully load the page.
+  self.serverRespondsWithContent = YES;
+  [ChromeEarlGrey loadURL:self.testServer->GetURL("/echo-query?foo")];
+  [ChromeEarlGrey waitForWebViewContainingText:"foo"];
+
+  // Reload the page, no response leads to ERR_INTERNET_DISCONNECTED error.
+  self.serverRespondsWithContent = NO;
+  [ChromeEarlGrey reload];
+  [ChromeEarlGrey waitForStaticHTMLViewContainingText:GetErrorMessage()];
+}
+
+// Sucessfully loads the page, goes back, stops the server, goes forward and
+// reloads.
+- (void)testGoForwardAfterServerIsDownAndReload {
+  // First page loads sucessfully.
+  [ChromeEarlGrey loadURL:self.testServer->GetURL("/echo")];
+  [ChromeEarlGrey waitForWebViewContainingText:"Echo"];
+
+  // Second page loads sucessfully.
+  self.serverRespondsWithContent = YES;
+  [ChromeEarlGrey loadURL:self.testServer->GetURL("/echo-query?foo")];
+  [ChromeEarlGrey waitForWebViewContainingText:"foo"];
+
+  // Go back to the first page.
+  [ChromeEarlGrey goBack];
+  [ChromeEarlGrey waitForWebViewContainingText:"Echo"];
+
+#if TARGET_IPHONE_SIMULATOR
+  // Go forward. The response will be retrieved from the page cache and will not
+  // present the error page. Page cache may not always exist on device (which is
+  // more memory constrained), so this part of the test is simulator-only.
+  self.serverRespondsWithContent = NO;
+  [ChromeEarlGrey goForward];
+  [ChromeEarlGrey waitForWebViewContainingText:"foo"];
+
+  // Reload bypasses the cache.
+  [ChromeEarlGrey reload];
+  [ChromeEarlGrey waitForStaticHTMLViewContainingText:GetErrorMessage()];
+#endif  // TARGET_IPHONE_SIMULATOR
+}
+
+// Sucessfully loads the page, then loads the URL which fails to load, then
+// sucessfully goes back to the first page.
+- (void)testGoBackFromErrorPage {
+  // First page loads sucessfully.
+  [ChromeEarlGrey loadURL:self.testServer->GetURL("/echo")];
+  [ChromeEarlGrey waitForWebViewContainingText:"Echo"];
+
+  // Second page fails to load.
+  [ChromeEarlGrey loadURL:self.testServer->GetURL("/close-socket")];
+  [ChromeEarlGrey waitForStaticHTMLViewContainingText:GetErrorMessage()];
+
+  // Going back should sucessfully load the first page.
+  [ChromeEarlGrey goBack];
+  [ChromeEarlGrey waitForWebViewContainingText:"Echo"];
+}
+
 // Loads the URL which redirects to unresponsive server.
 - (void)testRedirectToFailingURL {
   // No response leads to ERR_INTERNET_DISCONNECTED error.