Unify Android Webview and Chrome's fling

android_webview/native/aw_contents.cc

Index: android_webview/native/aw_contents.cc
diff --git a/android_webview/native/aw_contents.cc b/android_webview/native/aw_contents.cc
index c7af67fb7f51d095989becbfe15a2c361f37295c..b4fde1749b7d39ea666995d11102e847615b6570 100644
--- a/android_webview/native/aw_contents.cc
+++ b/android_webview/native/aw_contents.cc
@@ -938,6 +938,15 @@ void AwContents::SetBackgroundColor(JNIEnv* env, jobject obj, jint color) {
   render_view_host_ext_->SetBackgroundColor(color);
 }
 
+void AwContents::OnComputeScroll(JNIEnv* env,
+                                 jobject obj,
+                                 jlong animation_time_millis) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  browser_view_renderer_.OnComputeScroll(
+      base::TimeTicks() +
+      base::TimeDelta::FromMilliseconds(animation_time_millis));

[boliu, 2015/05/29 19:42:47]

Does this addition make sense?

Documentation on currentAnimationTimeMillis says it is *not* the "wall" clock.

[hush (inactive), 2015/06/05 21:47:22]

I am not exactly sure here. We have confusing usage of time related functions,
some of which are wrong in my opinion.

For example, I looked at some example in ContentViewCore.java where we pass
SystemClock.uptimeMillis() to construct a WebInputEvent. According to
documentation here:
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...
You are supposed to pass the time since epoch, so SystemClock.currentTimeMillis
is the right one.
I filed crbug.com/497323 for it.

For the comment about currentAnimationTimeMillis, I think it is right by looking
at the code. What's important for the animation tick is the difference between
each tick, but not the absolute value of each timer tick. We're consistently
passing currentAnimationTimeMillis to InputHandlerProxy to tick the animation.
So we're fine.
https://code.google.com/p/chromium/codesearch#chromium/src/content/renderer/i...

+}
+
 jlong AwContents::ReleasePopupAwContents(JNIEnv* env, jobject obj) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   return reinterpret_cast<intptr_t>(pending_contents_.release());
@@ -967,13 +976,13 @@ void AwContents::ScrollContainerViewTo(gfx::Vector2d new_value) {
       env, obj.obj(), new_value.x(), new_value.y());
 }
 
-bool AwContents::IsFlingActive() const {
+bool AwContents::IsSmoothScrollingActive() const {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   JNIEnv* env = AttachCurrentThread();
   ScopedJavaLocalRef<jobject> obj = java_ref_.get(env);
   if (obj.is_null())
     return false;
-  return Java_AwContents_isFlingActive(env, obj.obj());
+  return Java_AwContents_isSmoothScrollingActive(env, obj.obj());
 }
 
 void AwContents::UpdateScrollState(gfx::Vector2d max_scroll_offset,
@@ -997,14 +1006,16 @@ void AwContents::UpdateScrollState(gfx::Vector2d max_scroll_offset,
                                     max_page_scale_factor);
 }
 
-void AwContents::DidOverscroll(gfx::Vector2d overscroll_delta) {
+void AwContents::DidOverscroll(gfx::Vector2d overscroll_delta,
+                               gfx::Vector2dF overscroll_velocity) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   JNIEnv* env = AttachCurrentThread();
   ScopedJavaLocalRef<jobject> obj = java_ref_.get(env);
   if (obj.is_null())
     return;
-  Java_AwContents_didOverscroll(
-      env, obj.obj(), overscroll_delta.x(), overscroll_delta.y());
+  Java_AwContents_didOverscroll(env, obj.obj(), overscroll_delta.x(),
+                                overscroll_delta.y(), overscroll_velocity.x(),
+                                overscroll_velocity.y());
 }
 
 void AwContents::SetDipScale(JNIEnv* env, jobject obj, jfloat dip_scale) {