UI documentation fixes

Make the 'learn' section on the index page consistent with the nav bar
tab. Prompt 'views' doc up a bit, and use an image(credit to @ellyjones)
instead of ASCII diagram for better understanding.

Bug: none
Change-Id: Iac2c59e3c28a0f5021bc398ffad80929435a797c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2417072Reviewed-by: Robert Liao <robliao@chromium.org>
Commit-Queue: Robert Liao <robliao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#808583}

docs/ui/index.md

@@ -16,9 +16,9 @@ Recipes to help you work with Chrome UI.
 Details on Chrome UI.
 
 * [Best Practices](/docs/ui/learn/index.md#best-practices)
+* [Views](/docs/ui/views/overview.md)
 * [Product Excellence](/docs/ui/product_excellence/index.md)
 * [UI Devtools](/docs/ui/ui_devtools/index.md)
-* [Views](/docs/ui/views/overview.md)
 
 Archival Documentation on Chrome UI.
 * [Aura](/docs/ui/aura/index.md)

docs/ui/learn/index.md

@@ -6,5 +6,18 @@
 * [Layout](bestpractices/layout.md): How to use Views layout.
 * [Ownership](bestpractices/ownership.md): How to manage Views object lifetimes.
 
-# Architecture Overview
-Coming soon.
+# Chrome UI
+
+* [Views](/docs/ui/views/overview.md)
+* [Product Excellence](/docs/ui/product_excellence/index.md)
+* [UI Devtools](/docs/ui/ui_devtools/index.md)
+
+# Archival Documentation on Chrome UI.
+
+* [Aura](/docs/ui/aura/index.md)
+* [Compositor](/docs/ui/compositor/index.md)
+
+# Processes
+
+* [Frontline Triage Procedures](frontline_triage.md)
+

docs/ui/views/overview.md

@@ -132,19 +132,7 @@ affecting the client view.
 
 The overall structure of a Widget and its helper Views looks like this:
 
-```
-(Widget
-  (RootView
-    (NonClientView
-      (NonClientFrameView
-        title
-        non-client buttons, e.g. close button
-        ...)
-      (ClientView
-        contents
-        dialog buttons
-        ...))))
-```
+![views](views.png)
 
 ## Dialogs