Notify OverscrollController of gesture events in plugins.

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 ef9fcafce86f38870e825feb8b61a89d939074e0..6243aa0d1f12d562085e23bd7aa78ec9fe2d7185 100644
--- a/content/browser/renderer_host/overscroll_controller.cc
+++ b/content/browser/renderer_host/overscroll_controller.cc
@@ -32,8 +32,8 @@ bool IsGestureEventFromTouchpad(const blink::WebInputEvent& event) {
 namespace content {
 
 OverscrollController::OverscrollController()
-    : overscroll_mode_(OVERSCROLL_NONE),
-      scroll_state_(STATE_UNKNOWN),
+    : scroll_state_(STATE_UNKNOWN),
+      overscroll_mode_(OVERSCROLL_NONE),
       overscroll_delta_x_(0.f),
       overscroll_delta_y_(0.f),
       delegate_(NULL) {}
@@ -51,6 +51,16 @@ bool OverscrollController::ShouldProcessEvent(
     case blink::WebInputEvent::kGestureScrollEnd: {
       const blink::WebGestureEvent& gesture =
           static_cast<const blink::WebGestureEvent&>(event);
+
+      // GestureScrollBegin and GestureScrollEnd events are created to wrap
+      // individual resent GestureScrollUpdates from a plugin. Hence these
+      // should not be used to indicate the beginning/end of the overscroll.
+      // TODO(mcnee): When we remove BrowserPlugin, delete this code.
+      // See crbug.com/533069
+      if (gesture.resending_plugin_id != -1 &&
+          event.GetType() != blink::WebInputEvent::kGestureScrollUpdate)
+        return false;
+
       blink::WebGestureEvent::ScrollUnits scrollUnits;
       switch (event.GetType()) {
         case blink::WebInputEvent::kGestureScrollBegin: