Bug 1573720 - Convert ui.touch_activation.duration_ms to a static pref. r=botond

The commit also adds a missing StaticPrefs_dom.h include for APZEventState.cpp.

Differential Revision: https://phabricator.services.mozilla.com/D41915

--HG--
extra : moz-landing-system : lando

gfx/layers/apz/util/APZEventState.cpp

@@ -35,6 +35,8 @@
 #include "nsLayoutUtils.h"
 #include "nsIScrollableFrame.h"
 #include "nsIScrollbarMediator.h"
+#include "mozilla/StaticPrefs_dom.h"
+#include "mozilla/StaticPrefs_ui.h"
 #include "mozilla/TouchEvents.h"
 #include "mozilla/widget/nsAutoRollup.h"
 
@@ -93,9 +95,6 @@ int32_t WidgetModifiersToDOMModifiers(mozilla::Modifiers aModifiers) {
 namespace mozilla {
 namespace layers {
 
-static int32_t sActiveDurationMs = 10;
-static bool sActiveDurationMsSet = false;
-
 APZEventState::APZEventState(nsIWidget* aWidget,
                              ContentReceivedInputBlockCallback&& aCallback)
     : mWidget(nullptr)  // initialized in constructor body
@@ -113,13 +112,6 @@ APZEventState::APZEventState(nsIWidget* aWidget,
   MOZ_ASSERT(NS_SUCCEEDED(rv),
              "APZEventState constructed with a widget that"
              " does not support weak references. APZ will NOT work!");
-
-  if (!sActiveDurationMsSet) {
-    Preferences::AddIntVarCache(&sActiveDurationMs,
-                                "ui.touch_activation.duration_ms",
-                                sActiveDurationMs);
-    sActiveDurationMsSet = true;
-  }
 }
 
 APZEventState::~APZEventState() {}
@@ -203,8 +195,9 @@ void APZEventState::ProcessSingleTap(const CSSPoint& aPoint,
   }
   RefPtr<DelayedFireSingleTapEvent> callback = new DelayedFireSingleTapEvent(
       mWidget, ldPoint, aModifiers, aClickCount, timer, touchRollup);
-  nsresult rv = timer->InitWithCallback(callback, sActiveDurationMs,
-                                        nsITimer::TYPE_ONE_SHOT);
+  nsresult rv = timer->InitWithCallback(
+      callback, StaticPrefs::ui_touch_activation_duration_ms(),
+      nsITimer::TYPE_ONE_SHOT);
   if (NS_FAILED(rv)) {
     // Make |callback| not hold the timer, so they will both be destructed when
     // we leave the scope of this function.

modules/libpref/init/StaticPrefList.yaml

@@ -6484,6 +6484,14 @@
   value: 100
   mirror: always
 
+# If the user has clicked an element, how long do we keep the :active state
+# before it is cleared by the mouse sequences fired after a
+# touchstart/touchend.
+- name: ui.touch_activation.duration_ms
+  type: int32_t
+  value: 10
+  mirror: always
+
 # Prevent system colors from being exposed to CSS or canvas.
 - name: ui.use_standins_for_native_colors
   type: RelaxedAtomicBool

modules/libpref/init/all.js

@@ -4965,11 +4965,6 @@ pref("gfx.vr.osvr.clientKitLibPath", "");
 // are rejecting frames, it determines the rate at which RAF callbacks will be called.
 pref("dom.vr.display.rafMaxDuration", 50);
 
-// If the user has clicked an element, how long do we keep the
-// :active state before it is cleared by the mouse sequences
-// fired after a touchstart/touchend.
-pref("ui.touch_activation.duration_ms", 10);
-
 // nsMemoryInfoDumper can watch a fifo in the temp directory and take various
 // actions when the fifo is written to.  Disable this in general.
 pref("memory_info_dumper.watch_fifo.enabled", false);