Add a WebContentsImpl API to snapshot the accessibility tree.

content/browser/frame_host/render_frame_host_impl.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/frame_host/render_frame_host_impl.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/containers/hash_tables.h"
 #include "base/lazy_instance.h"
@@ skipping 46 matching lines @@
 #include "content/public/browser/permission_type.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/stream_handle.h"
 #include "content/public/browser/user_metrics.h"
 #include "content/public/common/content_constants.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/common/url_constants.h"
 #include "content/public/common/url_utils.h"
 #include "ui/accessibility/ax_tree.h"
+#include "ui/accessibility/ax_tree_update.h"
 #include "url/gurl.h"
 
 #if defined(OS_MACOSX)
 #include "content/browser/frame_host/popup_menu_helper_mac.h"
 #endif
 
 #if defined(ENABLE_MEDIA_MOJO_RENDERER)
 #include "media/mojo/interfaces/media_renderer.mojom.h"
 #include "media/mojo/services/mojo_renderer_service.h"
 #endif
@@ skipping 297 matching lines @@
     IPC_MESSAGE_HANDLER(FrameHostMsg_BeginNavigation,
                         OnBeginNavigation)
     IPC_MESSAGE_HANDLER(FrameHostMsg_DispatchLoad, OnDispatchLoad)
     IPC_MESSAGE_HANDLER(FrameHostMsg_TextSurroundingSelectionResponse,
                         OnTextSurroundingSelectionResponse)
     IPC_MESSAGE_HANDLER(AccessibilityHostMsg_Events, OnAccessibilityEvents)
     IPC_MESSAGE_HANDLER(AccessibilityHostMsg_LocationChanges,
                         OnAccessibilityLocationChanges)
     IPC_MESSAGE_HANDLER(AccessibilityHostMsg_FindInPageResult,
                         OnAccessibilityFindInPageResult)
+    IPC_MESSAGE_HANDLER(AccessibilityHostMsg_SnapshotResponse,
+                        OnAccessibilitySnapshotResponse)
     IPC_MESSAGE_HANDLER(FrameHostMsg_ToggleFullscreen, OnToggleFullscreen)
     // The following message is synthetic and doesn't come from RenderFrame, but
     // from RenderProcessHost.
     IPC_MESSAGE_HANDLER(FrameHostMsg_RenderProcessGone, OnRenderProcessGone)
 #if defined(OS_MACOSX) || defined(OS_ANDROID)
     IPC_MESSAGE_HANDLER(FrameHostMsg_ShowPopup, OnShowPopup)
     IPC_MESSAGE_HANDLER(FrameHostMsg_HidePopup, OnHidePopup)
 #endif
   IPC_END_MESSAGE_MAP()
 
@@ skipping 677 matching lines @@
 
   if (frame_tree_node_->IsMainFrame()) {
     // RenderViewHost/RenderWidgetHost needs to reset some stuff.
     render_view_host_->RendererExited(
         render_view_host_->render_view_termination_status_, exit_code);
 
     render_view_host_->delegate_->RenderViewTerminated(
         render_view_host_, static_cast<base::TerminationStatus>(status),
         exit_code);
   }
+
+  // Execute any pending AX tree snapshot callbacks with an empty response,
+  // since we're never going to get a response from this renderer.
+  for (auto iter = ax_tree_snapshot_callbacks_.begin();

[dcheng, 2015/04/10 22:49:00]

for (const auto& iter : ax_tree_snapshot_callbacks_)

[dmazzoni, 2015/04/13 06:37:18]

Done.

+       iter != ax_tree_snapshot_callbacks_.end();
+       ++iter) {
+    iter->second.Run(ui::AXTreeUpdate());
+  }
+  ax_tree_snapshot_callbacks_.clear();
 }
 
 void RenderFrameHostImpl::OnSwappedOut() {
   // Ignore spurious swap out ack.
   if (rfh_state_ != STATE_PENDING_SWAP_OUT)
     return;
 
   TRACE_EVENT_ASYNC_END0("navigation", "RenderFrameHostImpl::SwapOut", this);
   swapout_event_monitor_timeout_->Stop();
 
@@ skipping 294 matching lines @@
     BrowserAccessibilityManager* manager =
         GetOrCreateBrowserAccessibilityManager();
     if (manager) {
       manager->OnFindInPageResult(
           params.request_id, params.match_index, params.start_id,
           params.start_offset, params.end_id, params.end_offset);
     }
   }
 }
 
+void RenderFrameHostImpl::OnAccessibilitySnapshotResponse(
+    int callback_id,
+    const ui::AXTreeUpdate& snapshot) {
+  std::map<int, AXTreeSnapshotCallback>::iterator it =
+      ax_tree_snapshot_callbacks_.find(callback_id);
+  if (it != ax_tree_snapshot_callbacks_.end()) {
+    it->second.Run(snapshot);
+    ax_tree_snapshot_callbacks_.erase(it);
+  } else {
+    NOTREACHED() << "Received AX tree snapshot response for unknown id";
+  }
+}
+
 void RenderFrameHostImpl::OnToggleFullscreen(bool enter_fullscreen) {
   if (enter_fullscreen)
     delegate_->EnterFullscreenMode(GetLastCommittedURL().GetOrigin());
   else
     delegate_->ExitFullscreenMode();
 
   // The previous call might change the fullscreen state. We need to make sure
   // the renderer is aware of that, which is done via the resize message.
   render_view_host_->WasResized();
 }
@@ skipping 393 matching lines @@
   // As a sanity check, make sure the frame belongs to the same BrowserContext.
   CHECK_EQ(GetSiteInstance()->GetBrowserContext(),
            other_render_frame_host->GetSiteInstance()->GetBrowserContext());
   return GetSiteInstance() == other_render_frame_host->GetSiteInstance();
 }
 
 void RenderFrameHostImpl::SetAccessibilityMode(AccessibilityMode mode) {
   Send(new FrameMsg_SetAccessibilityMode(routing_id_, mode));
 }
 
+void RenderFrameHostImpl::RequestAXTreeSnapshot(
+    AXTreeSnapshotCallback callback) {
+  static int next_id = 1;
+  int callback_id = next_id++;
+  Send(new AccessibilityMsg_SnapshotTree(routing_id_, callback_id));
+  ax_tree_snapshot_callbacks_.insert(std::make_pair(callback_id, callback));
+}
+
 void RenderFrameHostImpl::SetAccessibilityCallbackForTesting(
     const base::Callback<void(ui::AXEvent, int)>& callback) {
   accessibility_testing_callback_ = callback;
 }
 
 void RenderFrameHostImpl::SetTextTrackSettings(
     const FrameMsg_TextTrackSettings_Params& params) {
   DCHECK(!GetParent());
   Send(new FrameMsg_SetTextTrackSettings(routing_id_, params));
 }
@@ skipping 137 matching lines @@
     return;
 
   permission_manager->RegisterPermissionUsage(
       PermissionType::GEOLOCATION,
       GetLastCommittedURL().GetOrigin(),
       frame_tree_node()->frame_tree()->GetMainFrame()
           ->GetLastCommittedURL().GetOrigin());
 }
 
 }  // namespace content