Synthetic pinch gesture take scale factor as parameter.

content/browser/renderer_host/input/synthetic_gesture_target_android.cc

Index: content/browser/renderer_host/input/synthetic_gesture_target_android.cc
diff --git a/content/browser/renderer_host/input/synthetic_gesture_target_android.cc b/content/browser/renderer_host/input/synthetic_gesture_target_android.cc
index 91792c2a8ad77d8d0b0723ffd34e683674ef2d7d..b8989f57993c9c405524af0ebff4784c5c093e53 100644
--- a/content/browser/renderer_host/input/synthetic_gesture_target_android.cc
+++ b/content/browser/renderer_host/input/synthetic_gesture_target_android.cc
@@ -98,4 +98,11 @@ int SyntheticGestureTargetAndroid::GetTouchSlopInDips() const {
   return gfx::ViewConfiguration::GetTouchSlopInPixels() / device_scale_factor;
 }
 
+int SyntheticGestureTargetAndroid::GetMinScalingSpanInDips() const {
+  float device_scale_factor =
+      gfx::Screen::GetNativeScreen()->GetPrimaryDisplay().device_scale_factor();
+  return
+      gfx::ViewConfiguration::GetMinScalingSpanInPixels() / device_scale_factor;
+}
+
 }  // namespace content