Touch emulator: create/destroy gesture provider on the fly.

content/browser/renderer_host/input/touch_emulator.h

Index: content/browser/renderer_host/input/touch_emulator.h
diff --git a/content/browser/renderer_host/input/touch_emulator.h b/content/browser/renderer_host/input/touch_emulator.h
index 9ddb725342736c0235e6aedc9da45cecd1a1c7be..ea74f6292f849e06a94a8a600453a2595355ce81 100644
--- a/content/browser/renderer_host/input/touch_emulator.h
+++ b/content/browser/renderer_host/input/touch_emulator.h
@@ -25,7 +25,7 @@ class CONTENT_EXPORT TouchEmulator : public ui::GestureProviderClient {
 
   // Note that TouchEmulator should always listen to touch events and their acks
   // (even in disabled state) to track native stream presence.
-  bool enabled() const { return enabled_; }
+  bool enabled() const { return gesture_provider_; }
 
   // Returns |true| if the event was consumed. Consumed event should not
   // propagate any further.
@@ -71,11 +71,11 @@ class CONTENT_EXPORT TouchEmulator : public ui::GestureProviderClient {
   void HandleEmulatedTouchEvent(blink::WebTouchEvent event);
 
   TouchEmulatorClient* const client_;
-  ui::FilteredGestureProvider gesture_provider_;
 
+  // Emulator is enabled iff gesture provider is created.
   // Disabled emulator does only process touch acks left from previous
   // emulation. It does not intercept any events.
-  bool enabled_;
+  scoped_ptr<ui::FilteredGestureProvider> gesture_provider_;
 
   // While emulation is on, default cursor is touch. Pressing shift changes
   // cursor to the pinch one.