[Android] Avoid early fling termination if initial time is non-positive

content/child/fling_animator_impl_android.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/child/fling_animator_impl_android.h"
 
 #include "base/logging.h"
 #include "third_party/WebKit/public/platform/WebFloatSize.h"
 #include "third_party/WebKit/public/platform/WebGestureCurveTarget.h"
 #include "ui/gfx/frame_time.h"
@@ skipping 48 matching lines @@
 void FlingAnimatorImpl::CancelFling() {
   if (!is_active_)
     return;
 
   is_active_ = false;
   scroller_.AbortAnimation();
 }
 
 bool FlingAnimatorImpl::apply(double time,
                               blink::WebGestureCurveTarget* target) {
+  // If the fling has yet to start, simply return and report true to prevent
+  // fling termination.
+  if (time <= 0)
+    return true;
+
   const base::TimeTicks time_ticks =
       base::TimeTicks() + base::TimeDelta::FromMicroseconds(
                               time * base::Time::kMicrosecondsPerSecond);
   if (!scroller_.ComputeScrollOffset(time_ticks)) {
     is_active_ = false;
     return false;
   }
 
   gfx::PointF current_position(scroller_.GetCurrX(), scroller_.GetCurrY());
   gfx::Vector2dF scroll_amount(current_position - last_position_);
   last_position_ = current_position;
 
   // scrollBy() could delete this curve if the animation is over, so don't touch
   // any member variables after making that call.
   return target->scrollBy(blink::WebFloatSize(scroll_amount),
                           blink::WebFloatSize(scroller_.GetCurrVelocityX(),
                                               scroller_.GetCurrVelocityY()));
 }
 
 FlingAnimatorImpl* FlingAnimatorImpl::CreateAndroidGestureCurve(
     const blink::WebFloatPoint& velocity,
     const blink::WebSize&) {
   FlingAnimatorImpl* gesture_curve = new FlingAnimatorImpl();
   gesture_curve->StartFling(velocity);
   return gesture_curve;
 }
 
 }  // namespace content