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diff --git a/gfx/config/gfxConfig.h b/gfx/config/gfxConfig.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef mozilla_gfx_config_gfxConfig_h
+#define mozilla_gfx_config_gfxConfig_h
+
+#include <functional>
+#include "gfxFeature.h"
+#include "gfxFallback.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/EnumSet.h"
+#include "mozilla/Maybe.h"
+
+namespace mozilla {
+namespace gfx {
+
+// Defined in GraphicsMessages.ipdlh.
+class DevicePrefs;
+class FeatureFailure;
+
+// Manages the history and state of a graphics feature. The flow of a feature
+// is:
+//   - A default value, set by all.js, or gfxPlatform.
+//   - A user value, set by an external value or user pref.
+//   - An environment value, determined by system/hardware factors or
+//   nsIGfxInfo.
+//   - A runtime value, determined by any failures encountered after enabling
+//     the feature.
+//
+// Each state change for a feature is recorded in this class.
+class gfxConfig {
+ public:
+  // Return the full state history of a feature.
+  static FeatureState& GetFeature(Feature aFeature);
+
+  // Query whether a parameter is enabled, taking into account any user or
+  // runtime overrides. The algorithm works as follow:
+  //
+  //  1. If a runtime decision disabled the feature, return false.
+  //  2. If the user force-enabled the feature, return true.
+  //  3. If the environment disabled the feature, return false.
+  //  4. If the user specified a decision, return it.
+  //  5. Return the base setting for the feature.
+  static bool IsEnabled(Feature aFeature);
+
+  // Query the history of a parameter. ForcedOnByUser returns whether or not
+  // the user specifically used a "force" preference to enable the parameter.
+  // IsDisabledByDefault returns whether or not the initial status of the
+  // feature, before adding user prefs and runtime decisions, was disabled.
+  static bool IsForcedOnByUser(Feature aFeature);
+
+  // This returns true if the feature was disabled by default, or was never
+  // initialized to begin with.
+  static bool IsDisabledByDefault(Feature aFeature);
+
+  // Query the status value of a parameter. This is computed similar to
+  // IsEnabled:
+  //
+  //  1. If a runtime failure was set, return it.
+  //  2. If the user force-enabled the feature, return ForceEnabled.
+  //  3. If an environment status was set, return it.
+  //  4. If a user status was set, return it.
+  //  5. Return the default status.
+  static FeatureStatus GetValue(Feature aFeature);
+
+  // Reset the entire state of a feature.
+  static void Reset(Feature aFeature);
+
+  // Initialize the base value of a parameter. The return value is aEnable.
+  static bool SetDefault(Feature aFeature, bool aEnable,
+                         FeatureStatus aDisableStatus,
+                         const char* aDisableMessage);
+  static void DisableByDefault(Feature aFeature, FeatureStatus aDisableStatus,
+                               const char* aDisableMessage,
+                               const nsACString& aFailureId = ""_ns);
+  static void EnableByDefault(Feature aFeature);
+
+  // Inherit a computed value from another process.
+  static void Inherit(Feature aFeature, FeatureStatus aStatus);
+
+  // Inherit a set of computed values from another process.
+  static void Inherit(EnumSet<Feature> aFeatures,
+                      const DevicePrefs& aDevicePrefs);
+
+  // Set a environment status that overrides both the default and user
+  // statuses; this should be used to disable features based on system
+  // or hardware problems that can be determined up-front. The only
+  // status that can override this decision is the user force-enabling
+  // the feature.
+  static void Disable(Feature aFeature, FeatureStatus aStatus,
+                      const char* aMessage,
+                      const nsACString& aFailureId = ""_ns);
+
+  // Given a preference name, infer the default value and whether or not the
+  // user has changed it. |aIsEnablePref| specifies whether or not the pref
+  // is intended to enable a feature (true), or disable it (false).
+  static void SetDefaultFromPref(Feature aFeature, const char* aPrefName,
+                                 bool aIsEnablePref, bool aDefaultValue);
+
+  // Disable a parameter based on a runtime decision. This permanently
+  // disables the feature, since runtime decisions override all other
+  // decisions.
+  static void SetFailed(Feature aFeature, FeatureStatus aStatus,
+                        const char* aMessage,
+                        const nsACString& aFailureId = ""_ns);
+
+  // Force a feature to be disabled permanently. This is the same as
+  // SetFailed(), but the name may be clearer depending on the context.
+  static void ForceDisable(Feature aFeature, FeatureStatus aStatus,
+                           const char* aMessage,
+                           const nsACString& aFailureId = ""_ns) {
+    SetFailed(aFeature, aStatus, aMessage, aFailureId);
+  }
+
+  // Convenience helpers for SetFailed().
+  static bool MaybeSetFailed(Feature aFeature, bool aEnable,
+                             FeatureStatus aDisableStatus,
+                             const char* aDisableMessage,
+                             const nsACString& aFailureId = ""_ns) {
+    if (!aEnable) {
+      SetFailed(aFeature, aDisableStatus, aDisableMessage, aFailureId);
+      return false;
+    }
+    return true;
+  }
+
+  // Convenience helper for SetFailed().
+  static bool MaybeSetFailed(Feature aFeature, FeatureStatus aStatus,
+                             const char* aDisableMessage,
+                             const nsACString& aFailureId = ""_ns) {
+    return MaybeSetFailed(aFeature,
+                          (aStatus != FeatureStatus::Available &&
+                           aStatus != FeatureStatus::ForceEnabled),
+                          aStatus, aDisableMessage, aFailureId);
+  }
+
+  // Re-enables a feature that was previously disabled, by attaching it to a
+  // fallback. The fallback inherits the message that was used for disabling
+  // the feature. This can be used, for example, when D3D11 fails at runtime
+  // but we acquire a second, successful device with WARP.
+  static void Reenable(Feature aFeature, Fallback aFallback);
+
+  // Same as SetDefault, except if the feature already has a default value
+  // set, the new value will be set as a runtime value. This is useful for
+  // when the base value can change (for example, via an update from the
+  // parent process).
+  static bool InitOrUpdate(Feature aFeature, bool aEnable,
+                           FeatureStatus aDisableStatus,
+                           const char* aDisableMessage);
+
+  // Set a user status that overrides the base value (but not runtime value)
+  // of a parameter.
+  static void UserEnable(Feature aFeature, const char* aMessage);
+  static void UserForceEnable(Feature aFeature, const char* aMessage);
+  static void UserDisable(Feature aFeature, const char* aMessage,
+                          const nsACString& aFailureId = ""_ns);
+
+  // Query whether a fallback has been toggled.
+  static bool UseFallback(Fallback aFallback);
+
+  // Add a log entry denoting that a given fallback had to be used. This can
+  // be called from any thread in the UI or GPU process.
+  static void EnableFallback(Fallback aFallback, const char* aMessage);
+
+  // Run a callback for each initialized FeatureState.
+  typedef std::function<void(const char* aName, const char* aDescription,
+                             FeatureState& aFeature)>
+      FeatureIterCallback;
+  static void ForEachFeature(const FeatureIterCallback& aCallback);
+
+  // Run a callback for each enabled fallback.
+  typedef std::function<void(const char* aName, const char* aMsg)>
+      FallbackIterCallback;
+  static void ForEachFallback(const FallbackIterCallback& aCallback);
+
+  // Get the most descriptive failure id message for this feature.
+  static const nsCString& GetFailureId(Feature aFeature);
+
+  static void ImportChange(Feature aFeature,
+                           const Maybe<FeatureFailure>& aChange);
+
+  static void Init();
+  static void Shutdown();
+
+ private:
+  void ForEachFallbackImpl(const FallbackIterCallback& aCallback);
+
+ private:
+  FeatureState& GetState(Feature aFeature) {
+    MOZ_ASSERT(size_t(aFeature) < kNumFeatures);
+    return mFeatures[size_t(aFeature)];
+  }
+  const FeatureState& GetState(Feature aFeature) const {
+    MOZ_ASSERT(size_t(aFeature) < kNumFeatures);
+    return mFeatures[size_t(aFeature)];
+  }
+
+  bool UseFallbackImpl(Fallback aFallback) const;
+  void EnableFallbackImpl(Fallback aFallback, const char* aMessage);
+
+ private:
+  static const size_t kNumFeatures = size_t(Feature::NumValues);
+  static const size_t kNumFallbacks = size_t(Fallback::NumValues);
+
+ private:
+  FeatureState mFeatures[kNumFeatures];
+  uint64_t mFallbackBits;
+
+ private:
+  struct FallbackLogEntry {
+    Fallback mFallback;
+    char mMessage[80];
+  };
+
+  FallbackLogEntry mFallbackLog[kNumFallbacks];
+  size_t mNumFallbackLogEntries;
+};
+
+}  // namespace gfx
+}  // namespace mozilla
+
+#endif  // mozilla_gfx_config_gfxConfig_h