Allow zoom-in as alternative to popup when tapping multiple targets.

content/public/common/renderer_preferences.h

Index: content/public/common/renderer_preferences.h
diff --git a/content/public/common/renderer_preferences.h b/content/public/common/renderer_preferences.h
index 7735ca3d3277fdb93d2e4f5ab9fc469ba0ac692c..bc5447a3e4f21114d608702dc8189baf2dc6d778 100644
--- a/content/public/common/renderer_preferences.h
+++ b/content/public/common/renderer_preferences.h
@@ -37,6 +37,13 @@ enum RendererPreferencesSubpixelRenderingEnum {
   RENDERER_PREFERENCES_SUBPIXEL_RENDERING_VBGR,
 };
 
+enum TapMultipleTargetsStrategy {
+  TAP_MULTIPLE_TARGETS_STRATEGY_ZOOM = 0,
+  TAP_MULTIPLE_TARGETS_STRATEGY_POPUP,
+
+  TAP_MULTIPLE_TARGETS_STRATEGY_MAX = TAP_MULTIPLE_TARGETS_STRATEGY_POPUP,
+};
+
 struct CONTENT_EXPORT RendererPreferences {
   RendererPreferences();
   ~RendererPreferences();
@@ -126,6 +133,9 @@ struct CONTENT_EXPORT RendererPreferences {
 
   // Controls deacceleration of touchscreen-initiated flings.
   std::vector<float> touchscreen_fling_profile;
+
+  // How to handle a tap gesture touching multiple targets
+  TapMultipleTargetsStrategy tap_multiple_targets_strategy;
 };
 
 }  // namespace content