Refactor edge of screen detection code.

There were two resources that both defined the edge of the screen.

Change-Id: I82ab553cc3123ef54ff1f0c692d29f3678ad04ac
diff --git a/src/com/android/launcher3/Launcher.java b/src/com/android/launcher3/Launcher.java
index 9a42513..0540249 100644
--- a/src/com/android/launcher3/Launcher.java
+++ b/src/com/android/launcher3/Launcher.java
@@ -316,7 +316,6 @@
     private UserEventDispatcher mUserEventDispatcher;
 
     private float mLastDispatchTouchEventX = 0.0f;
-    private float mEdgeOfScreenThresholdPx = 0.0f;
 
     public ViewGroupFocusHelper mFocusHandler;
     private boolean mRotationEnabled = false;
@@ -395,9 +394,6 @@
 
         setContentView(R.layout.launcher);
 
-        mEdgeOfScreenThresholdPx = getResources()
-                .getDimensionPixelSize(R.dimen.edge_of_screen_threshold);
-
         setupViews();
         mDeviceProfile.layout(this, false /* notifyListeners */);
         mExtractedColors = new ExtractedColors();
@@ -2718,8 +2714,8 @@
         }
 
 
-        boolean ignoreLongPressToOverview = mDeviceProfile.shouldIgnoreLongPressToOverview(
-                mLastDispatchTouchEventX, mEdgeOfScreenThresholdPx);
+        boolean ignoreLongPressToOverview =
+                mDeviceProfile.shouldIgnoreLongPressToOverview(mLastDispatchTouchEventX);
 
         if (v instanceof Workspace) {
             if (!mWorkspace.isInOverviewMode()) {