Don't set shownRatio in main thread top controls on animated state change.

third_party/WebKit/Source/web/WebViewImpl.cpp

Index: third_party/WebKit/Source/web/WebViewImpl.cpp
diff --git a/third_party/WebKit/Source/web/WebViewImpl.cpp b/third_party/WebKit/Source/web/WebViewImpl.cpp
index 7f9d5c550cfe56d0f26f919d9bc120bda193ac41..3de3c9e437114d6f73ac264da187ebba51ab5124 100644
--- a/third_party/WebKit/Source/web/WebViewImpl.cpp
+++ b/third_party/WebKit/Source/web/WebViewImpl.cpp
@@ -1831,6 +1831,17 @@ void WebViewImpl::performResize()
 void WebViewImpl::updateTopControlsState(WebTopControlsState constraint, WebTopControlsState current, bool animate)
 {
     topControls().updateConstraints(constraint);
+
+    // If the change should be animated, let the impl thread drive the change.
+    // Otherwise, immediately set the shown ratio so we don't have to wait for
+    // a commit from the impl thread.
+    if (!animate) {
+        if (current == WebTopControlsShown)
+            topControls().setShownRatio(1.f);
+        else if (current == WebTopControlsHidden)
+            topControls().setShownRatio(0.f);

[majidvp, 2016/06/28 19:52:20]

Maybe it is worth it to specifically call out the TopControlsBoth case is a
no-op.
Perhaps this should become a switch statement instead?

[bokan, 2016/06/28 23:15:33]

Done.

+    }

[majidvp, 2016/06/28 19:52:20]

Why move the clamping logic out of top controls? I think this is internal logic
to TopControls and it is better to pass in animate boolean to the method
instead.

[bokan, 2016/06/28 23:15:33]

Done.

+
     if (m_layerTreeView)
         m_layerTreeView->updateTopControlsState(constraint, current, animate);
 }