Revert 46567 - Reimplement accessibility of web content by caching the entire

accessibility tree in the browser process.

Adds new RPCs for a browser tab to request accessibility info from
a renderer; the renderer responds with a complete tree of
accessibility metadata for the entire DOM, which is then cached
in the RenderWidgetHostView. This part is crossplatform and will
help with accessibility on both Windows and Mac OS X.

For Windows, MSAA support for web content has been rewritten to
use this new cache. Tested in JAWS and NVDA screen readers.
Using Chrome with a screen reader is now fast and stable,
unlike the previous implementation. However, note that most
advanced functionality is still not supported, and much work remains
to make Chrome work well with a screen reader. This is a necessary
step to improve stability first.

BUG=25564
BUG=13291
TEST=See http://codereview.chromium.org/1806001

Review URL: http://codereview.chromium.org/1637018

TBR=dmazzoni@chromium.org
Review URL: http://codereview.chromium.org/2031004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@46642 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 52 insertions, 15 deletions

diff --git a/chrome/renderer/render_thread.h b/chrome/renderer/render_thread.h
index f2ea2c3..680668c 100644
--- a/chrome/renderer/render_thread.h
+++ b/chrome/renderer/render_thread.h
@@ -261,8 +261,6 @@ class RenderThread : public RenderThreadBase,
 
   void OnGpuChannelEstablished(const IPC::ChannelHandle& channel_handle);
 
-  void OnGetAccessibilityTree();
-
   // Gather usage statistics from the in-memory cache and inform our host.
   // These functions should be call periodically so that the host can make
   // decisions about how to allocation resources using current information.
diff --git a/chrome/renderer/render_view.cc b/chrome/renderer/render_view.cc
index 339ae18..2aea82a 100644
--- a/chrome/renderer/render_view.cc
+++ b/chrome/renderer/render_view.cc
@@ -74,6 +74,7 @@
 #include "skia/ext/image_operations.h"
 #include "third_party/cld/encodings/compact_lang_det/win/cld_unicodetext.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebAccessibilityCache.h"
+#include "third_party/WebKit/WebKit/chromium/public/WebAccessibilityObject.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebCString.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebDataSource.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebDevToolsAgent.h"
@@ -635,6 +636,9 @@ void RenderView::OnMessageReceived(const IPC::Message& message) {
         ViewMsg_GetSerializedHtmlDataForCurrentPageWithLocalLinks,
         OnGetSerializedHtmlDataForCurrentPageWithLocalLinks)
     IPC_MESSAGE_HANDLER(ViewMsg_GetApplicationInfo, OnGetApplicationInfo)
+    IPC_MESSAGE_HANDLER(ViewMsg_GetAccessibilityInfo, OnGetAccessibilityInfo)
+    IPC_MESSAGE_HANDLER(ViewMsg_ClearAccessibilityInfo,
+                        OnClearAccessibilityInfo)
     IPC_MESSAGE_HANDLER(ViewMsg_ShouldClose, OnMsgShouldClose)
     IPC_MESSAGE_HANDLER(ViewMsg_ClosePage, OnClosePage)
     IPC_MESSAGE_HANDLER(ViewMsg_ThemeChanged, OnThemeChanged)
@@ -680,7 +684,6 @@ void RenderView::OnMessageReceived(const IPC::Message& message) {
                         OnCustomContextMenuAction)
     IPC_MESSAGE_HANDLER(ViewMsg_TranslatePage, OnTranslatePage)
     IPC_MESSAGE_HANDLER(ViewMsg_RevertTranslation, OnRevertTranslation)
-    IPC_MESSAGE_HANDLER(ViewMsg_GetAccessibilityTree, OnGetAccessibilityTree)
 
     // Have the super handle all other messages.
     IPC_MESSAGE_UNHANDLED(RenderWidget::OnMessageReceived(message))
@@ -1331,10 +1334,14 @@ void RenderView::UpdateURL(WebFrame* frame) {
   // we don't want the transition type to persist.  Just clear it.
   navigation_state->set_transition_type(PageTransition::LINK);
 
+#if defined(OS_WIN)
   if (accessibility_.get()) {
-    accessibility_->clear();
+    // Remove accessibility info cache.
     accessibility_.reset();
   }
+#else
+  // TODO(port): accessibility not yet implemented. See http://crbug.com/8288.
+#endif
 }
 
 // Tell the embedding application that the title of the active page has changed
@@ -3904,16 +3911,46 @@ void RenderView::OnUpdateBrowserWindowId(int window_id) {
   browser_window_id_ = window_id;
 }
 
-void RenderView::OnGetAccessibilityTree() {
-  if (accessibility_.get()) {
+void RenderView::OnGetAccessibilityInfo(
+    const webkit_glue::WebAccessibility::InParams& in_params,
+    webkit_glue::WebAccessibility::OutParams* out_params) {
+#if defined(OS_WIN)
+  if (!accessibility_.get()) {
+    // TODO(dglazkov): Once implemented for all ports, remove lazy
+    // instantiation of accessibility_.
+    accessibility_.reset(WebAccessibilityCache::create());
+    accessibility_->initialize(webview());
+  }
+
+  out_params->return_code =
+      webkit_glue::WebAccessibility::GetAccObjInfo(accessibility_.get(),
+                                                  in_params,
+                                                  out_params);
+
+#else  // defined(OS_WIN)
+  // TODO(port): accessibility not yet implemented
+  NOTIMPLEMENTED();
+#endif
+}
+
+void RenderView::OnClearAccessibilityInfo(int acc_obj_id, bool clear_all) {
+#if defined(OS_WIN)
+  if (!accessibility_.get()) {
+    // If accessibility is not activated, ignore clearing message.
+    return;
+  }
+
+  if (clear_all) {
     accessibility_->clear();
+    return;
   }
-  accessibility_.reset(WebAccessibilityCache::create());
-  accessibility_->initialize(webview());
 
-  WebAccessibilityObject src_tree = webview()->accessibilityObject();
-  webkit_glue::WebAccessibility dst_tree(src_tree, accessibility_.get());
-  Send(new ViewHostMsg_AccessibilityTree(routing_id_, dst_tree));
+  accessibility_->remove(acc_obj_id);
+
+#else  // defined(OS_WIN)
+  // TODO(port): accessibility not yet implemented
+  NOTIMPLEMENTED();
+#endif
 }
 
 void RenderView::OnGetAllSavableResourceLinksForCurrentPage(
diff --git a/chrome/renderer/render_view.h b/chrome/renderer/render_view.h
index 0b4b2ab..bc68296 100644
--- a/chrome/renderer/render_view.h
+++ b/chrome/renderer/render_view.h
@@ -45,7 +45,6 @@
 #include "gfx/rect.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "testing/gtest/include/gtest/gtest_prod.h"
-#include "third_party/WebKit/WebKit/chromium/public/WebAccessibilityObject.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebConsoleMessage.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebContextMenuData.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebFrameClient.h"
@@ -497,8 +496,6 @@ class RenderView : public RenderWidget,
   // UserScript::DOCUMENT_IDLE.
   void OnUserScriptIdleTriggered(WebKit::WebFrame* frame);
 
-  void OnGetAccessibilityTree();
-
 #if defined(OS_MACOSX)
   // Helper routines for GPU plugin support. Used by the
   // WebPluginDelegateProxy, which has a pointer to the RenderView.
@@ -732,6 +729,10 @@ class RenderView : public RenderWidget,
   void OnExecuteCode(const ViewMsg_ExecuteCode_Params& params);
   void ExecuteCodeImpl(WebKit::WebFrame* frame,
                        const ViewMsg_ExecuteCode_Params& params);
+  void OnGetAccessibilityInfo(
+      const webkit_glue::WebAccessibility::InParams& in_params,
+      webkit_glue::WebAccessibility::OutParams* out_params);
+  void OnClearAccessibilityInfo(int acc_obj_id, bool clear_all);
 
   void OnExtensionMessageInvoke(const std::string& function_name,
                                 const ListValue& args,
@@ -1062,10 +1063,11 @@ class RenderView : public RenderWidget,
   bool decrement_shared_popup_at_destruction_;
 
   // TODO(port): revisit once we have accessibility
-
+#if defined(OS_WIN)
   // Handles accessibility requests into the renderer side, as well as
   // maintains the cache and other features of the accessibility tree.
   scoped_ptr<WebKit::WebAccessibilityCache> accessibility_;
+#endif
 
   // Resource message queue. Used to queue up resource IPCs if we need
   // to wait for an ACK from the browser before proceeding.