Add ios_web_view_shell_egtests target and accessibility labels to shell.

ios/web_view/shell/test/earl_grey/web_view_shell_matchers.mm

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import "ios/web_view/shell/test/earl_grey/web_view_shell_matchers.h"
+
+#include "base/mac/foundation_util.h"
+#include "base/strings/sys_string_conversions.h"
+#import "ios/testing/wait_util.h"
+#import "ios/web_view/shell/shell_view_controller.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+namespace ios_web_view {
+
+id<GREYMatcher> AddressFieldText(const std::string& text) {
+  MatchesBlock matches = ^BOOL(UIView* view) {
+    if (![view isKindOfClass:[UITextField class]]) {
+      return NO;
+    }
+    if (![[view accessibilityLabel]
+            isEqualToString:kWebViewShellAddressFieldAccessibilityLabel]) {
+      return NO;
+    }
+    UITextField* text_field = base::mac::ObjCCastStrict<UITextField>(view);
+    NSString* error_message = [NSString
+        stringWithFormat:
+            @"Address field text did not match. expected: %@, actual: %@",
+            base::SysUTF8ToNSString(text), text_field.text];
+    bool success = testing::WaitUntilConditionOrTimeout(
+        testing::kWaitForUIElementTimeout, ^{
+          return base::SysNSStringToUTF8(text_field.text) == text;
+        });
+    GREYAssert(success, error_message);
+    return YES;
+  };
+
+  DescribeToBlock describe = ^(id<GREYDescription> description) {
+    [description appendText:@"address field containing "];
+    [description appendText:base::SysUTF8ToNSString(text)];
+  };
+
+  return [[GREYElementMatcherBlock alloc] initWithMatchesBlock:matches
+                                              descriptionBlock:describe];
+}
+
+id<GREYMatcher> BackButton() {
+  return grey_accessibilityLabel(kWebViewShellBackButtonAccessibilityLabel);
+}
+
+id<GREYMatcher> ForwardButton() {
+  return grey_accessibilityLabel(kWebViewShellForwardButtonAccessibilityLabel);
+}
+
+id<GREYMatcher> AddressField() {
+  return grey_accessibilityLabel(kWebViewShellAddressFieldAccessibilityLabel);
+}
+
+}  // namespace ios_web_view