Bug 962278 - Adjust default APZ DPI and settings that depend on it. r=kats

gfx/layers/composite/APZCTreeManager.cpp

@@ -28,7 +28,7 @@
 namespace mozilla {
 namespace layers {
 
-float APZCTreeManager::sDPI = 72.0;
+float APZCTreeManager::sDPI = 160.0;
 
 APZCTreeManager::APZCTreeManager()
     : mTreeLock("APZCTreeLock"),

gfx/layers/ipc/AsyncPanZoomController.cpp

@@ -140,7 +140,7 @@ static bool gTouchActionPropertyEnabled = false;
  * accidentally processing taps as touch moves, and from very short/accidental
  * touches moving the screen.
  */
-static float gTouchStartTolerance = 1.0f/2.0f;
+static float gTouchStartTolerance = 1.0f/4.5f;
 
 /**
  * Default touch behavior (is used when not touch behavior is set).