Bug 1282306 - More correctly describe APZ touch support in about:support. r=botond

Instead of just reporting the value of the pref, also make sure that about:support
incorporates the runtime check of whether or not a touch device was discovered
in the widget code. The code to do this already exists in TouchEvent::PrefEnabled,
so we can just reuse that.

MozReview-Commit-ID: DN7FSlsDwD1

--HG--
extra : rebase_source : efb3d66e1669f8f2b038888ef2b1c8bb83f1c710

gfx/thebes/gfxAndroidPlatform.h

@@ -66,10 +66,6 @@ public:
 
     virtual already_AddRefed<mozilla::gfx::VsyncSource> CreateHardwareVsyncSource() override;
 
-    virtual bool SupportsApzTouchInput() const override {
-      return true;
-    }
-
 protected:
     bool AccelerateLayersByDefault() override {
       return true;

gfx/thebes/gfxPlatform.cpp

@@ -137,6 +137,7 @@ class mozilla::gl::SkiaGLGlue : public GenericAtomicRefCounted {
 #include "SoftwareVsyncSource.h"
 #include "nscore.h" // for NS_FREE_PERMANENT_DATA
 #include "mozilla/dom/ContentChild.h"
+#include "mozilla/dom/TouchEvent.h"
 #include "gfxVR.h"
 #include "VRManagerChild.h"
 #include "mozilla/gfx/GPUParent.h"
@@ -2644,6 +2645,12 @@ gfxPlatform::ImportGPUDeviceData(const mozilla::gfx::GPUDeviceData& aData)
   gfxConfig::ImportChange(Feature::OPENGL_COMPOSITING, aData.oglCompositing());
 }
 
+bool
+gfxPlatform::SupportsApzTouchInput() const
+{
+  return dom::TouchEvent::PrefEnabled(nullptr);
+}
+
 bool
 gfxPlatform::SupportsApzDragInput() const
 {

gfx/thebes/gfxPlatform.h

@@ -626,9 +626,7 @@ public:
     virtual bool SupportsApzWheelInput() const {
       return false;
     }
-    virtual bool SupportsApzTouchInput() const {
-      return false;
-    }
+    bool SupportsApzTouchInput() const;
     bool SupportsApzDragInput() const;
 
     virtual void FlushContentDrawing() {}

gfx/thebes/gfxPlatformGtk.cpp

@@ -909,11 +909,4 @@ gfxPlatformGtk::CreateHardwareVsyncSource()
   return gfxPlatform::CreateHardwareVsyncSource();
 }
 
-bool
-gfxPlatformGtk::SupportsApzTouchInput() const
-{
-  int value = gfxPrefs::TouchEventsEnabled();
-  return value == 1 || value == 2;
-}
-
 #endif

gfx/thebes/gfxPlatformGtk.h

@@ -123,8 +123,6 @@ public:
       return true;
     }
 
-    bool SupportsApzTouchInput() const override;
-
     void FontsPrefsChanged(const char *aPref) override;
 
     // maximum number of fonts to substitute for a generic

gfx/thebes/gfxWindowsPlatform.cpp

@@ -1878,13 +1878,6 @@ gfxWindowsPlatform::CreateHardwareVsyncSource()
   return d3dVsyncSource.forget();
 }
 
-bool
-gfxWindowsPlatform::SupportsApzTouchInput() const
-{
-  int value = gfxPrefs::TouchEventsEnabled();
-  return value == 1 || value == 2;
-}
-
 void
 gfxWindowsPlatform::GetAcceleratedCompositorBackends(nsTArray<LayersBackend>& aBackends)
 {

gfx/thebes/gfxWindowsPlatform.h

@@ -209,7 +209,6 @@ public:
     bool SupportsApzWheelInput() const override {
       return true;
     }
-    bool SupportsApzTouchInput() const override;
 
     // Recreate devices as needed for a device reset. Returns true if a device
     // reset occurred.

gfx/thebes/moz.build

@@ -248,6 +248,7 @@ include('/ipc/chromium/chromium-config.mozbuild')
 FINAL_LIBRARY = 'xul'
 
 LOCAL_INCLUDES += [
+    '/dom/base',
     '/dom/workers',
     '/dom/xml',
 ]