Create EarlGrey wait utility.

EarlGrey typically handles synchronization with the UI, but it is
useful when manipulating non-UI APIs to be able to wait for a certain
state.

BUG=610837

Review-Url: https://codereview.chromium.org/2044433003
Cr-Commit-Position: refs/heads/master@{#398182}

ios/testing/earl_grey/BUILD.gn

@@ -9,6 +9,11 @@ config("earl_grey_support_config") {
 
 source_set("earl_grey_support") {
   testonly = true
+
+  deps = [
+    "//ios/third_party/earl_grey",
+  ]
+
   sources = [
     "wait_util.h",
     "wait_util.mm",

ios/testing/earl_grey/earl_grey_support.gyp

@@ -10,6 +10,9 @@
       # GN version: //ios/testing/earl_grey:earl_grey_support
       'target_name': 'earl_grey_support',
       'type': 'static_library',
+      'dependencies': [
+        '<(DEPTH)/ios/third_party/earl_grey/earl_grey.gyp:EarlGrey',
+      ],
       'sources': [
         'wait_util.h',
         'wait_util.mm',

ios/testing/earl_grey/wait_util.h

@@ -17,6 +17,10 @@ extern const NSTimeInterval kWaitForUIElementTimeout;
 
 // Constant for timeout in seconds while waiting for JavaScript completion.
 extern const NSTimeInterval kWaitForJSCompletionTimeout;
-}
+
+// Waits until |condition| is true, or induces GREYAssert after |timeout|.
+void WaitUntilCondition(NSTimeInterval timeout, bool (^condition)(void));
+
+}  // namespace testing
 
 #endif  // IOS_TESTING_EARL_GREY_WAIT_UTIL_H_
\ No newline at end of file

ios/testing/earl_grey/wait_util.mm

@@ -4,9 +4,24 @@
 
 #include "ios/testing/earl_grey/wait_util.h"
 
+#import <EarlGrey/EarlGrey.h>
+
+#include "base/test/ios/wait_util.h"
+
 namespace testing {
 
 const NSTimeInterval kSpinDelaySeconds = 0.01;
-const NSTimeInterval kWaitForUIElementTimeout = 4.0;
 const NSTimeInterval kWaitForJSCompletionTimeout = 2.0;
+const NSTimeInterval kWaitForUIElementTimeout = 4.0;
+
+void WaitUntilCondition(NSTimeInterval timeout, bool (^condition)(void)) {
+  NSDate* deadline = [NSDate dateWithTimeIntervalSinceNow:timeout];
+  while (!condition() &&
+         [[NSDate date] compare:deadline] != NSOrderedDescending) {
+    base::test::ios::SpinRunLoopWithMaxDelay(
+        base::TimeDelta::FromSecondsD(testing::kSpinDelaySeconds));
+  }
+  GREYAssert(condition(), @"Timeout waiting for condition.");
 }
+
+}  // namespace testing

ios/web/public/test/web_view_interaction_test_util.mm

@@ -27,14 +27,9 @@ void TapWebViewElementWithId(web::WebState* web_state,
         did_complete = true;
       }));
 
-  // TODO(crbug.com/610837): Re-factor wait code into common location.
-  NSDate* deadline = [NSDate
-      dateWithTimeIntervalSinceNow:testing::kWaitForJSCompletionTimeout];
-  while (([[NSDate date] compare:deadline] != NSOrderedDescending) &&
-         !did_complete) {
-    base::test::ios::SpinRunLoopWithMaxDelay(
-        base::TimeDelta::FromSecondsD(testing::kSpinDelaySeconds));
-  }
+  testing::WaitUntilCondition(testing::kWaitForJSCompletionTimeout, ^{
+    return did_complete;
+  });
 }
 
 }  // namespace test

ios/web/shell/test/earl_grey/shell_matchers.mm

@@ -54,16 +54,10 @@ id<GREYMatcher> addressField() {
       return NO;
     }
     UITextField* textField = base::mac::ObjCCastStrict<UITextField>(view);
-    NSDate* deadline =
-        [NSDate dateWithTimeIntervalSinceNow:testing::kWaitForUIElementTimeout];
-    while ([[NSDate date] compare:deadline] != NSOrderedDescending) {
-      if ([textField.text isEqualToString:base::SysUTF8ToNSString(text)]) {
-        return YES;
-      }
-      base::test::ios::SpinRunLoopWithMaxDelay(
-          base::TimeDelta::FromSecondsD(testing::kSpinDelaySeconds));
-    }
-    return NO;
+    testing::WaitUntilCondition(testing::kWaitForUIElementTimeout, ^bool() {
+      return [textField.text isEqualToString:base::SysUTF8ToNSString(text)];
+    });
+    return YES;
   };
 
   DescribeToBlock describe = ^(id<GREYDescription> description) {