Revert of Mac: Enable two finger double-tap smart zoom (patchset #1 id:1 of...

Revert of Mac: Enable two finger double-tap smart zoom (patchset #1 id:1 of https://codereview.chromium.org/909633002/)

Reason for revert:
This is a suspect in the dramatic increase in crash rates noted
in crbug.com/456860.

The crashes are on 10.10, so there are no stack traces, so this
is just a guess.

Original issue's description:
> Mac: Enable two finger double-tap smart zoom
>
> BUG=452592
>
> Committed: https://crrev.com/e69b4fd53dbf2d4c1fdc82de623186d7b21c29fb
> Cr-Commit-Position: refs/heads/master@{#315214}

TBR=avi@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=452592

Review URL: https://codereview.chromium.org/859393005

Cr-Commit-Position: refs/heads/master@{#315340}

content/browser/renderer_host/render_widget_host_view_mac.mm

@@ -2271,13 +2271,6 @@ void RenderWidgetHostViewMac::OnDisplayMetricsChanged(
   [responderDelegate_ touchesEndedWithEvent:event];
 }
 
-- (void)smartMagnifyWithEvent:(NSEvent*)event {
-  const WebGestureEvent& smartMagnifyEvent =
-      WebInputEventFactory::gestureEvent(event, self);
-  renderWidgetHostView_->render_widget_host_->ForwardGestureEvent(
-      smartMagnifyEvent);
-}
-
 // This is invoked only on 10.8 or newer when the user taps a word using
 // three fingers.
 - (void)quickLookWithEvent:(NSEvent*)event {

content/renderer/render_view_impl.cc

@@ -1134,10 +1134,6 @@ void RenderView::ApplyWebPreferences(const WebPreferences& prefs,
 #if defined(OS_WIN)
   settings->setShowContextMenuOnMouseUp(true);
 #endif
-
-#if defined(OS_MACOSX)
-  settings->setDoubleTapToZoomEnabled(true);
-#endif
 }
 
 /*static*/