Make IsWKWebViewEnabled not query field trial, command line flags.

ios/chrome/browser/experimental_flags.h

 // Copyright 2014 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.
 
 #ifndef IOS_CHROME_BROWSER_EXPERIMENTAL_FLAGS_H_
 #define IOS_CHROME_BROWSER_EXPERIMENTAL_FLAGS_H_
 
 #include <string>
 
 // This file can be empty. Its purpose is to contain the relatively short lived
@@ skipping 10 matching lines @@
 // Sets whether or not the field trial for WKWebView should be enabled. This
 // must be called at most once, and before IsWKWebViewEnabled. If this is never
 // called, IsWKWebViewEnabled will assume ineligibility.
 // Note that an explicit command line flag will ignore this setting; it controls
 // only whether the trial state will be checked in the default state.
 void SetWKWebViewTrialEligibility(bool eligible);
 
 // Whether the lru snapshot cache experiment is enabled.
 bool IsLRUSnapshotCacheEnabled();
 
-// Whether the app uses WKWebView instead of UIWebView.
-// The returned value will not change within a given session.
+// TODO(crbug.com/579697): This always returns true; cleanup codepaths that use
+// this.
 bool IsWKWebViewEnabled();
 
 // Whether the user would be put into a control group for the WKWebView
 // experiment assuming they were eligible. Calling this will *not* activate a
 // trial, so is safe to call without checking eligibility.
 bool IsTargetedToWKWebViewExperimentControlGroup();
 
 // Whether the user is part of a control group for the WKWebView experiment.
 bool IsInWKWebViewExperimentControlGroup();
 
 // Whether viewing and copying passwords is enabled.
 bool IsViewCopyPasswordsEnabled();
 
 // Whether password generation is enabled.
 bool IsPasswordGenerationEnabled();
 
 // Whether password generation fields are determined using local heuristics
 // only.
 bool UseOnlyLocalHeuristicsForPasswordGeneration();
 
 // Whether the Tab Switcher is enabled for iPad or not.
 bool IsTabSwitcherEnabled();
 
 }  // namespace experimental_flags
 
 #endif  // IOS_CHROME_BROWSER_EXPERIMENTAL_FLAGS_H_