Disabled pinch zooming in non-browser Aura windows.

ui/views/controls/webview/webview.cc

Index: ui/views/controls/webview/webview.cc
diff --git a/ui/views/controls/webview/webview.cc b/ui/views/controls/webview/webview.cc
index 0a7734e0656b79569b1c36764fb1005dcd9f9175..151aeb92d5148f1abf75762920e4f17dd5256816 100644
--- a/ui/views/controls/webview/webview.cc
+++ b/ui/views/controls/webview/webview.cc
@@ -12,6 +12,7 @@
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_view.h"
 #include "ipc/ipc_message.h"
+#include "third_party/WebKit/public/web/WebInputEvent.h"
 #include "ui/base/accessibility/accessibility_types.h"
 #include "ui/base/accessibility/accessible_view_state.h"
 #include "ui/events/event.h"
@@ -191,6 +192,15 @@ bool WebView::EmbedsFullscreenWidget() const {
   return embed_fullscreen_widget_mode_enabled_;
 }
 
+bool WebView::PreHandleGestureEvent(
+    content::WebContents* source,
+    const blink::WebGestureEvent& event) {
+  // Disable pinch zooming.
+  return event.type == blink::WebGestureEvent::GesturePinchBegin ||
+      event.type == blink::WebGestureEvent::GesturePinchUpdate ||
+      event.type == blink::WebGestureEvent::GesturePinchEnd;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // WebView, content::WebContentsObserver implementation: