Enable gestures for wheel events on all platforms other than MacOSX.

content/browser/renderer_host/overscroll_controller.cc

Index: content/browser/renderer_host/overscroll_controller.cc
diff --git a/content/browser/renderer_host/overscroll_controller.cc b/content/browser/renderer_host/overscroll_controller.cc
index b622dc8533807e3a2d82635c6dde454e25cc4232..6072bfc3fd96557b949651d3bf73903c09a04e65 100644
--- a/content/browser/renderer_host/overscroll_controller.cc
+++ b/content/browser/renderer_host/overscroll_controller.cc
@@ -7,6 +7,7 @@
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "content/browser/renderer_host/overscroll_controller_delegate.h"
+#include "content/common/input/input_event_utils.h"
 #include "content/public/browser/overscroll_configuration.h"
 #include "content/public/common/content_switches.h"
 
@@ -19,6 +20,12 @@ bool IsScrollEndEffectEnabled() {
       switches::kScrollEndEffect) == "1";
 }
 
+bool IsGestureEventFromTouchscreen(const blink::WebInputEvent& event) {
+  const blink::WebGestureEvent& gesture =
+      static_cast<const blink::WebGestureEvent&>(event);
+  return gesture.sourceDevice == blink::WebGestureDeviceTouchscreen;
+}
+
 }  // namespace
 
 namespace content {
@@ -28,8 +35,8 @@ OverscrollController::OverscrollController()
       scroll_state_(STATE_UNKNOWN),
       overscroll_delta_x_(0.f),
       overscroll_delta_y_(0.f),
-      delegate_(NULL) {
-}
+      delegate_(NULL),
+      use_gesutre_wheel_scrolling_(UseGestureBasedWheelScrolling()) {}
 
 OverscrollController::~OverscrollController() {
 }
@@ -40,17 +47,24 @@ bool OverscrollController::WillHandleEvent(const blink::WebInputEvent& event) {
       overscroll_delta_x_ || overscroll_delta_y_) {
     switch (event.type) {
       case blink::WebInputEvent::GestureScrollEnd:
+        // Gesture scroll end is sent based on a timeout avoid
+        // resetting on events from the touchpad.
+        reset_scroll_state = IsGestureEventFromTouchscreen(event);
+        break;
+
       case blink::WebInputEvent::GestureFlingStart:
         reset_scroll_state = true;
         break;
 
       case blink::WebInputEvent::MouseWheel: {
-        const blink::WebMouseWheelEvent& wheel =
-            static_cast<const blink::WebMouseWheelEvent&>(event);
-        if (!wheel.hasPreciseScrollingDeltas ||
-            wheel.phase == blink::WebMouseWheelEvent::PhaseEnded ||
-            wheel.phase == blink::WebMouseWheelEvent::PhaseCancelled) {
-          reset_scroll_state = true;
+        if (!use_gesutre_wheel_scrolling_) {
+          const blink::WebMouseWheelEvent& wheel =
+              static_cast<const blink::WebMouseWheelEvent&>(event);
+          if (!wheel.hasPreciseScrollingDeltas ||
+              wheel.phase == blink::WebMouseWheelEvent::PhaseEnded ||
+              wheel.phase == blink::WebMouseWheelEvent::PhaseCancelled) {
+            reset_scroll_state = true;
+          }
         }
         break;
       }
@@ -95,6 +109,10 @@ bool OverscrollController::WillHandleEvent(const blink::WebInputEvent& event) {
 
 void OverscrollController::ReceivedEventACK(const blink::WebInputEvent& event,
                                             bool processed) {
+  if (use_gesutre_wheel_scrolling_ &&
+      event.type == blink::WebInputEvent::MouseWheel)
+    return;
+
   if (processed) {
     // If a scroll event is consumed by the page, i.e. some content on the page
     // has been scrolled, then there is not going to be an overscroll gesture,
@@ -142,6 +160,12 @@ bool OverscrollController::DispatchEventCompletesAction (
       event.type != blink::WebInputEvent::GestureFlingStart)
     return false;
 
+  // Gesture scroll end is sent based on a timeout avoid
+  // resetting on events from the touchpad.
+  if (event.type == blink::WebInputEvent::GestureScrollEnd &&
+      !IsGestureEventFromTouchscreen(event))
+    return false;
+
   if (!delegate_)
     return false;
 
@@ -192,13 +216,23 @@ bool OverscrollController::DispatchEventResetsState(
     const blink::WebInputEvent& event) const {
   switch (event.type) {
     case blink::WebInputEvent::MouseWheel: {
-      // Only wheel events with precise deltas (i.e. from trackpad) contribute
-      // to the overscroll gesture.
-      const blink::WebMouseWheelEvent& wheel =
-          static_cast<const blink::WebMouseWheelEvent&>(event);
-      return !wheel.hasPreciseScrollingDeltas;
+      if (use_gesutre_wheel_scrolling_) {
+        return false;
+      } else {
+        // Only wheel events with precise deltas (i.e. from trackpad) contribute
+        // to the overscroll gesture.
+        const blink::WebMouseWheelEvent& wheel =
+            static_cast<const blink::WebMouseWheelEvent&>(event);
+        return !wheel.hasPreciseScrollingDeltas;
+      }
     }
 
+    // Gesture scroll begin/ends come based on a timeout avoid
+    // resetting on events from the touchpad.
+    case blink::WebInputEvent::GestureScrollBegin:
+    case blink::WebInputEvent::GestureScrollEnd:
+      return IsGestureEventFromTouchscreen(event);
+
     case blink::WebInputEvent::GestureScrollUpdate:
     case blink::WebInputEvent::GestureFlingCancel:
       return false;
@@ -217,20 +251,19 @@ bool OverscrollController::ProcessEventForOverscroll(
     case blink::WebInputEvent::MouseWheel: {
       const blink::WebMouseWheelEvent& wheel =
           static_cast<const blink::WebMouseWheelEvent&>(event);
-      if (!wheel.hasPreciseScrollingDeltas)
+      if (use_gesutre_wheel_scrolling_ || !wheel.hasPreciseScrollingDeltas)
         break;
       event_processed =
           ProcessOverscroll(wheel.deltaX * wheel.accelerationRatioX,
-                            wheel.deltaY * wheel.accelerationRatioY,
-                            wheel.type);
+                            wheel.deltaY * wheel.accelerationRatioY, true);
       break;
     }
     case blink::WebInputEvent::GestureScrollUpdate: {
       const blink::WebGestureEvent& gesture =
           static_cast<const blink::WebGestureEvent&>(event);
-      event_processed = ProcessOverscroll(gesture.data.scrollUpdate.deltaX,
-                                          gesture.data.scrollUpdate.deltaY,
-                                          gesture.type);
+      event_processed = ProcessOverscroll(
+          gesture.data.scrollUpdate.deltaX, gesture.data.scrollUpdate.deltaY,
+          gesture.sourceDevice == blink::WebGestureDeviceTouchpad);
       break;
     }
     case blink::WebInputEvent::GestureFlingStart: {
@@ -270,15 +303,14 @@ bool OverscrollController::ProcessEventForOverscroll(
 
 bool OverscrollController::ProcessOverscroll(float delta_x,
                                              float delta_y,
-                                             blink::WebInputEvent::Type type) {
+                                             bool is_touchpad) {
   if (scroll_state_ != STATE_CONTENT_SCROLLING)
     overscroll_delta_x_ += delta_x;
   overscroll_delta_y_ += delta_y;
 
   float horiz_threshold = GetOverscrollConfig(
-      WebInputEvent::isGestureEventType(type) ?
-          OVERSCROLL_CONFIG_HORIZ_THRESHOLD_START_TOUCHSCREEN :
-          OVERSCROLL_CONFIG_HORIZ_THRESHOLD_START_TOUCHPAD);
+      is_touchpad ? OVERSCROLL_CONFIG_HORIZ_THRESHOLD_START_TOUCHPAD
+                  : OVERSCROLL_CONFIG_HORIZ_THRESHOLD_START_TOUCHSCREEN);
   float vert_threshold = GetOverscrollConfig(
       OVERSCROLL_CONFIG_VERT_THRESHOLD_START);
   if (fabs(overscroll_delta_x_) <= horiz_threshold &&