Convert chrome_earl_grey's goBack to compile under EG2.

goBack requires waitForPageToFinishLoading, so that is converted also.
The wait is moved from app-side to test-side using a GREYCondition.

Uses http://crrev.com/c/1578949 as a guideline.

Bug: 922813
Change-Id: I4e4616f5f9bc7857e89e28df01171d3167e396c3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1610548
Commit-Queue: ericale <ericale@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#661096}

ios/chrome/test/earl_grey/chrome_earl_grey.h

@@ -38,11 +38,25 @@ id ExecuteJavaScript(NSString* javascript, NSError* __autoreleasing* out_error);
 // will properly synchronize the UI for Earl Grey tests.
 @interface ChromeEarlGreyImpl : BaseEGTestHelperImpl
 
-#pragma mark - History Utilities
+#pragma mark - History Utilities (EG2)
 // Clears browsing history. Raises an EarlGrey exception if history is not
 // cleared within a timeout.
 - (void)clearBrowsingHistory;
 
+#pragma mark - Navigation Utilities (EG2)
+
+// Navigates back to the previous page and waits for the loading to complete
+// within a timeout, or a GREYAssert is induced.
+// TODO(crbug.com/963613): Change return type to void when
+// CHROME_EG_ASSERT_NO_ERROR is removed.
+- (NSError*)goBack;
+
+// Waits for the page to finish loading within a timeout, or a GREYAssert is
+// induced.
+// TODO(crbug.com/963613): Change return type to void when
+// CHROME_EG_ASSERT_NO_ERROR is removed.
+- (NSError*)waitForPageToFinishLoading;
+
 @end
 
 // Helpers that only compile under EarlGrey 1 are included in this "EG1"
@@ -85,12 +99,6 @@ id ExecuteJavaScript(NSString* javascript, NSError* __autoreleasing* out_error);
 // CHROME_EG_ASSERT_NO_ERROR is removed.
 - (NSError*)reload;
 
-// Navigates back to the previous page and waits for the loading to complete
-// within a timeout, or a GREYAssert is induced.
-// TODO(crbug.com/963613): Change return type to void when
-// CHROME_EG_ASSERT_NO_ERROR is removed.
-- (NSError*)goBack;
-
 // Navigates forward to the next page and waits for the loading to complete
 // within a timeout, or a GREYAssert is induced.
 // TODO(crbug.com/963613): Change return type to void when
@@ -120,12 +128,6 @@ id ExecuteJavaScript(NSString* javascript, NSError* __autoreleasing* out_error);
 // Closes the current tab and waits for the UI to complete.
 - (void)closeCurrentTab;
 
-// Waits for the page to finish loading within a timeout, or a GREYAssert is
-// induced.
-// TODO(crbug.com/963613): Change return type to void when
-// CHROME_EG_ASSERT_NO_ERROR is removed.
-- (NSError*)waitForPageToFinishLoading;
-
 // Taps html element with |elementID| in the current web view.
 - (NSError*)tapWebViewElementWithID:(NSString*)elementID WARN_UNUSED_RESULT;
 

ios/chrome/test/earl_grey/chrome_earl_grey.mm

@@ -39,9 +39,14 @@
 #endif
 
 using base::test::ios::kWaitForJSCompletionTimeout;
+using base::test::ios::kWaitForPageLoadTimeout;
 using base::test::ios::kWaitForUIElementTimeout;
 using base::test::ios::WaitUntilConditionOrTimeout;
 
+namespace {
+NSString* kWaitForPageToFinishLoadingError = @"Page did not finish loading";
+}
+
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
@@ -63,6 +68,26 @@ GREY_STUB_CLASS_IN_APP_MAIN_QUEUE(ChromeEarlGreyAppInterface)
   [[GREYUIThreadExecutor sharedInstance] drainUntilIdle];
 }
 
+- (NSError*)goBack {
+  [ChromeEarlGreyAppInterface goBack];
+
+  [self waitForPageToFinishLoading];
+  return nil;
+}
+
+- (NSError*)waitForPageToFinishLoading {
+  GREYCondition* finishedLoading = [GREYCondition
+      conditionWithName:kWaitForPageToFinishLoadingError
+                  block:^{
+                    return ![ChromeEarlGreyAppInterface isLoading];
+                  }];
+
+  bool pageLoaded = [finishedLoading waitWithTimeout:kWaitForPageLoadTimeout];
+  EG_TEST_HELPER_ASSERT_TRUE(pageLoaded, kWaitForPageToFinishLoadingError);
+
+  return nil;
+}
+
 @end
 
 // The helpers below only compile under EarlGrey1.
@@ -160,13 +185,6 @@ id ExecuteJavaScript(NSString* javascript,
   return nil;
 }
 
-- (NSError*)goBack {
-  [chrome_test_util::BrowserCommandDispatcherForMainBVC() goBack];
-  [self waitForPageToFinishLoading];
-
-  return nil;
-}
-
 - (NSError*)goForward {
   [chrome_test_util::BrowserCommandDispatcherForMainBVC() goForward];
   [self waitForPageToFinishLoading];
@@ -208,13 +226,6 @@ id ExecuteJavaScript(NSString* javascript,
   [[GREYUIThreadExecutor sharedInstance] drainUntilIdle];
 }
 
-- (NSError*)waitForPageToFinishLoading {
-  bool pageLoaded = chrome_test_util::WaitForPageToFinishLoading();
-  EG_TEST_HELPER_ASSERT_TRUE(pageLoaded, @"Page did not finish loading");
-
-  return nil;
-}
-
 - (NSError*)tapWebViewElementWithID:(NSString*)elementID {
   BOOL success =
       web::test::TapWebViewElementWithId(chrome_test_util::GetCurrentWebState(),

ios/chrome/test/earl_grey/chrome_earl_grey_app_interface.h

@@ -17,6 +17,12 @@
 // operation failed.
 + (NSError*)clearBrowsingHistory;
 
+// Returns YES if the current WebState is loading.
++ (BOOL)isLoading;
+
+// Navigates back to the previous page.
++ (void)goBack;
+
 @end
 
 #endif  // IOS_CHROME_TEST_EARL_GREY_CHROME_EARL_GREY_APP_INTERFACE_H_

ios/chrome/test/earl_grey/chrome_earl_grey_app_interface.mm

@@ -4,7 +4,9 @@
 
 #import "ios/chrome/test/earl_grey/chrome_earl_grey_app_interface.h"
 
+#import "ios/chrome/test/app/chrome_test_util.h"
 #import "ios/chrome/test/app/history_test_util.h"
+#include "ios/chrome/test/app/navigation_test_util.h"
 #import "ios/testing/nserror_util.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
@@ -22,4 +24,12 @@
       @"Clearing browser history timed out");
 }
 
++ (bool)isLoading {
+  return chrome_test_util::IsLoading();
+}
+
++ (void)goBack {
+  [chrome_test_util::BrowserCommandDispatcherForMainBVC() goBack];
+}
+
 @end