Organize docs/accessibility

./: overview docs

R=katie@chromium.org

platform-specific accessibility

browser: docs pertaining to Chrome browser e.g. web contents and
os: docs pertaining to Chrome OS
Change-Id: I8b0423503d3199b10c8038e6cb45435558db1461
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3255169
Commit-Queue: David Tseng <dtseng@chromium.org>
Reviewed-by: Katie Dektar <katie@chromium.org>
Cr-Commit-Position: refs/heads/main@{#936992}

docs/accessibility/browser/how_a11y_works.md

@@ -4,13 +4,13 @@ This document explains the technical details behind Chrome accessibility
 code by starting at a high level and progressively adding more levels of
 detail.
 
-Please read the accessibility [overview](overview.md) first.
+Please read the accessibility [overview](../overview.md) first.
 
 [TOC]
 
 ## Accessibility for a simple (non-browser) application
 
-As described in the [overview](overview.md), every platform has its own
+As described in the [overview](../overview.md), every platform has its own
 accessibility APIs that are used by both assistive technology and sometimes
 by automation software. To better understand the challenges of accessibility
 support in Chromium, let's first explore what it's like to build an

docs/accessibility/browser/tts.md

@@ -56,7 +56,7 @@ platform.
     forwards speech events to PATTS, or the network speech engine, or,
     coming soon, third-party speech engines.
 
-    - [PATTS](patts.md) is the built-in Chrome OS text-to-speech engine.
+    - [PATTS](../os/patts.md) is the built-in Chrome OS text-to-speech engine.
 
 ### Testing
 

docs/accessibility/os/espeak.md

@@ -4,7 +4,7 @@ Chrome OS comes with a port of the open-source eSpeak-NG speech synthesis
 engine. eSpeak-NG is lower quality than Google's "PATTS" speech engine,
 but it's faster, uses less resources, and supports more languages.
 
-[Read more about Text-to-Speech in Chrome](tts.md).
+[Read more about Text-to-Speech in Chrome](../browser/tts.md).
 
 [See also Google's "PATTS" speech engine](patts.md).
 

docs/accessibility/os/patts.md

@@ -3,7 +3,7 @@
 Chrome OS comes with a speech synthesis engine developed internally at Google
 called PATTS. It's based on the same engine that ships with all Android devices.
 
-[Read more about Text-to-Speech in Chrome](tts.md).
+[Read more about Text-to-Speech in Chrome](../browser/tts.md).
 
 [See also the eSpeak engine](espeak.md).
 

docs/accessibility/overview.md

@@ -218,11 +218,11 @@ Automation Inspector Chrome extension).
 ### Supported Platforms and APIs
 
 * Windows: IAccessible (also known as Microsoft Active Accessibility or MSAA),
-  IAccessible2, [UI Automation](uiautomation.md). Chromium also supports
+  IAccessible2, [UI Automation](browser/uiautomation.md). Chromium also supports
-  [mapping between IAccessible2 and UI Automation nodes](ia2_to_uia.md).
+  [mapping between IAccessible2 and UI Automation nodes](browser/ia2_to_uia.md).
 * Mac: NSAccessibility
 * Linux: ATK
-* Android: [AccessibilityNodeInfo and AccessibilityNodeProvider](android.md)
+* Android: [AccessibilityNodeInfo and AccessibilityNodeProvider](browser/android.md)
 
 ## Chromium's multi-process architecture
 
@@ -520,7 +520,9 @@ is defined by [automation.idl], which must be kept synchronized with
 
 ## Further reading
 
-For more detail, read [How Chrome Accessibility Works](how_a11y_works.md).
+For more detail on Chrome web contents and platform accessibility, read [How Chrome Accessibility Works](browser/how_a11y_works.md).
+
+# TODO(accessibility): write os equiavlent how does Chrome os a11y work.
 
 [ax.mojom.AXActionData]: https://source.chromium.org/chromium/chromium/src/+/main:ui/accessibility/mojom/ax_action_data.mojom;l=13
 [ax.mojom.RenderAccessibilityHost::HandleAXEvents()]: https://source.chromium.org/chromium/chromium/src/+/main:content/common/render_accessibility.mojom;l=47