Add live updates for AshDevToolsCSSAgent

ash/common/devtools/ash_devtools_css_agent.cc

Index: ash/common/devtools/ash_devtools_css_agent.cc
diff --git a/ash/common/devtools/ash_devtools_css_agent.cc b/ash/common/devtools/ash_devtools_css_agent.cc
index 295b53a3b35307921173814b2b0cca68196a8fe4..b7390fa563dfda71a4d4005f514a16adf38beeb5 100644
--- a/ash/common/devtools/ash_devtools_css_agent.cc
+++ b/ash/common/devtools/ash_devtools_css_agent.cc
@@ -59,10 +59,12 @@ std::unique_ptr<CSS::CSSStyle> BuildStyles(views::View* view) {
 AshDevToolsCSSAgent::AshDevToolsCSSAgent(AshDevToolsDOMAgent* dom_agent)
     : dom_agent_(dom_agent) {
   DCHECK(dom_agent_);
+  dom_agent_->AddObserver(this);
 }
 
 AshDevToolsCSSAgent::~AshDevToolsCSSAgent() {}
 
+// CSS:Backend implementation

[sadrul, 2016/11/25 18:39:23]

Remove comment. (from the following sections too)

[Sarmad Hashmi, 2016/11/26 01:44:37]

Done.

 ui::devtools::protocol::Response AshDevToolsCSSAgent::getMatchedStylesForNode(
     int nodeId,
     ui::devtools::protocol::Maybe<ui::devtools::protocol::CSS::CSSStyle>*
@@ -71,6 +73,49 @@ ui::devtools::protocol::Response AshDevToolsCSSAgent::getMatchedStylesForNode(
   return ui::devtools::protocol::Response::OK();
 }
 
+// AshDevToolsDOMAgentObserver implementation
+void AshDevToolsCSSAgent::OnWindowAdded(WmWindow* window) {
+  window->AddObserver(this);
+}
+
+void AshDevToolsCSSAgent::OnWindowRemoved(WmWindow* window) {
+  window->RemoveObserver(this);
+}
+
+void AshDevToolsCSSAgent::OnWidgetAdded(views::Widget* widget) {
+  widget->AddObserver(this);
+}
+
+void AshDevToolsCSSAgent::OnWidgetRemoved(views::Widget* widget) {
+  widget->RemoveObserver(this);
+}
+
+void AshDevToolsCSSAgent::OnViewAdded(views::View* view) {
+  view->AddObserver(this);
+}
+
+void AshDevToolsCSSAgent::OnViewRemoved(views::View* view) {
+  view->RemoveObserver(this);
+}
+
+// WmWindowObserver implementation
+void AshDevToolsCSSAgent::OnWindowBoundsChanged(WmWindow* window,

[sadrul, 2016/11/25 18:39:23]

Can we get these updates from the dom-agent as well, instead of having to
register with the Widget/View etc.?

[Sarmad Hashmi, 2016/11/26 01:44:37]

It's possible yes. It would definitely make the code less tedious. But, we would
be losing flexibility for the agents. For example, the AnimationAgent may need
to listen to OnWindowAdded changes and get the layer for the newly added window,
so it can listen to animations from it. We could either stick with this or have
DOM agent listen to layer animation stuff and notify the AnimationAgent.

[sadrul, 2016/11/29 02:02:58]

I think I still prefer for only the DOMAgent to install the observers, and the
rest of the agents can get update from that. (it may even make sense to take out
the observer-related code out of the DOMAgent at some point, but we don't need
to do that yet)

[Sarmad Hashmi, 2016/11/29 23:16:24]

Done.

+                                                const gfx::Rect& old_bounds,
+                                                const gfx::Rect& new_bounds) {
+  InvalidateStyleSheet();
+}
+
+// views::WidgetObserver implementation
+void AshDevToolsCSSAgent::OnWidgetBoundsChanged(views::Widget* widget,
+                                                const gfx::Rect& new_bounds) {
+  InvalidateStyleSheet();
+}
+
+// views::ViewObserver implementation
+void AshDevToolsCSSAgent::OnViewBoundsChanged(views::View* view) {
+  InvalidateStyleSheet();
+}
+
 std::unique_ptr<ui::devtools::protocol::CSS::CSSStyle>
 AshDevToolsCSSAgent::GetStylesForNode(int nodeId) {
   WmWindow* window = dom_agent_->GetWindowFromNodeId(nodeId);
@@ -89,5 +134,10 @@ AshDevToolsCSSAgent::GetStylesForNode(int nodeId) {
   return nullptr;
 }
 
+void AshDevToolsCSSAgent::InvalidateStyleSheet() {
+  // Pass in empty string just to invalidate all the styles on the frontend
+  frontend()->styleSheetChanged("");

[sadrul, 2016/11/25 18:39:23]

std::string() instead of ""

When you invalidate the style-sheet, do you have to rebuild the css props for
each node in the tree? Is it not possible to update the props of just one node,
of the View/Widget etc. that actually changed?

[Sarmad Hashmi, 2016/11/26 01:44:37]

Done.

We only build CSS props when a node is selected in the inspector. At this point,
GetMatchedStylesForNode is called and any results from GetMatchedStylesForNode
are cached in the frontend. When we call stylesheetChanged(), the frontend is
simply notified that any cached CSS styles should no longer be used so inspector
just requests styles for the selected nodes. Let me know if you need me to
clarify further!

[sadrul, 2016/11/29 02:02:58]

Is it possible to invalidate the cache for only the affected nodes, instead of
for all nodes?

[Sarmad Hashmi, 2016/11/29 23:16:24]

Assigned node_id as stylesheetid to each node as discussed.

+}
+
 }  // namespace devtools
 }  // namespace ash