[Android] Disable the touch ack timeout on mobile sites

content/browser/renderer_host/render_widget_host_impl.cc

Index: content/browser/renderer_host/render_widget_host_impl.cc
diff --git a/content/browser/renderer_host/render_widget_host_impl.cc b/content/browser/renderer_host/render_widget_host_impl.cc
index 93d865b4a0cae79c44829ff6986df497cf42f871..dd9fdb5805d9ee844385ad99455dcb9f449cc3ba 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -101,6 +101,21 @@ typedef base::hash_map<RenderWidgetHostID, RenderWidgetHostImpl*>
 base::LazyInstance<RoutingIDWidgetMap> g_routing_id_widget_map =
     LAZY_INSTANCE_INITIALIZER;
 
+int GetInputRouterViewFlagsFromCompositorFrameMetadata(
+    const cc::CompositorFrameMetadata metadata) {
+  int view_flags = InputRouter::VIEW_FLAGS_NONE;
+
+  if (metadata.min_page_scale_factor == metadata.max_page_scale_factor)
+    view_flags |= InputRouter::FIXED_PAGE_SCALE;
+
+  float window_width_dip =
+      metadata.page_scale_factor * metadata.viewport_size.width();
+  if (metadata.root_layer_size.width() <= window_width_dip)

[Xianzhu, 2014/01/14 21:54:19]

Can we simply skip timeout for all pages with viewport tag?

[jdduke (slow), 2014/01/14 21:56:38]

Where do we get that data?

[Xianzhu, 2014/01/14 23:56:18]

My fault. I thought it is available in the metadata.

[johnme, 2014/01/15 02:15:09]

No, many desktop sites have viewport tags like <meta name="viewport"
content="width=1024"> (including, say, theverge.com) and we shouldn't treat
those differently from other desktop sites.

+    view_flags |= InputRouter::MOBILE_VIEWPORT;
+
+  return view_flags;

[Xianzhu, 2014/01/14 21:54:19]

Will the individual bits of view_flags be meaningful to InputRouter or be used
for purpose other than touch_ack_timeout?

Raised the question when I was seeking other conditions to opt out the timeout,
which would need new bits, or just InputRouter::DisableTouchAckTimeout().

[jdduke (slow), 2014/01/14 21:56:38]

Currently, no, it's only useful for the ack timeout.  However, 
the flag additions were somewhat speculative... I've had thoughts of filtering
out pinch update events if the page scale is fixed, or event scroll updates if
we know there is no affordance in the scroll offset. 

+}
+
 // Implements the RenderWidgetHostIterator interface. It keeps a list of
 // RenderWidgetHosts, and makes sure it returns a live RenderWidgetHost at each
 // iteration (or NULL if there isn't any left).
@@ -1499,12 +1514,8 @@ bool RenderWidgetHostImpl::OnSwapCompositorFrame(
   uint32 output_surface_id = param.a;
   param.b.AssignTo(frame.get());
 
-  bool fixed_page_scale =
-      frame->metadata.min_page_scale_factor ==
-          frame->metadata.max_page_scale_factor;
-  int updated_view_flags = fixed_page_scale ? InputRouter::FIXED_PAGE_SCALE
-                                            : InputRouter::VIEW_FLAGS_NONE;
-  input_router_->OnViewUpdated(updated_view_flags);
+  input_router_->OnViewUpdated(
+      GetInputRouterViewFlagsFromCompositorFrameMetadata(frame->metadata));
 
   if (view_) {
     view_->OnSwapCompositorFrame(output_surface_id, frame.Pass());