Adds new experimental accessibility extension api to enable or disable native accessibility.

content/browser/accessibility/browser_accessibility_state_impl.cc

Index: content/browser/accessibility/browser_accessibility_state_impl.cc
diff --git a/content/browser/accessibility/browser_accessibility_state_impl.cc b/content/browser/accessibility/browser_accessibility_state_impl.cc
index 3cb73fe8a8e1656c440ca4537933d387e658a8e2..a7af6790938dd049ddc9964290c8f61708429992 100644
--- a/content/browser/accessibility/browser_accessibility_state_impl.cc
+++ b/content/browser/accessibility/browser_accessibility_state_impl.cc
@@ -7,7 +7,9 @@
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
 #include "base/timer.h"
+#include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/public/browser/browser_thread.h"
+#include "content/public/browser/render_process_host.h"
 #include "content/public/common/content_switches.h"
 #include "ui/gfx/sys_color_change_listener.h"
 
@@ -80,11 +82,15 @@ void BrowserAccessibilityStateImpl::OnScreenReaderDetected() {
   SetAccessibilityMode(AccessibilityModeComplete);
 }
 
-void BrowserAccessibilityStateImpl::OnAccessibilityEnabledManually() {
+void BrowserAccessibilityStateImpl::OnAccessibilityEnabledByExtensionAPI() {
   // We may want to do something different with this later.
   SetAccessibilityMode(AccessibilityModeComplete);
 }
 
+void BrowserAccessibilityStateImpl::OnAccessibilityDisabledByExtensionAPI() {
+  SetAccessibilityMode(AccessibilityModeOff);
+}
+
 bool BrowserAccessibilityStateImpl::IsAccessibleBrowser() {
   return (accessibility_mode_ == AccessibilityModeComplete);
 }
@@ -117,13 +123,32 @@ void BrowserAccessibilityStateImpl::UpdatePlatformSpecificHistograms() {
 }
 #endif
 
-AccessibilityMode BrowserAccessibilityStateImpl::GetAccessibilityMode() {
-  return accessibility_mode_;
-}
-
 void BrowserAccessibilityStateImpl::SetAccessibilityMode(
     AccessibilityMode mode) {
+  if (accessibility_mode_ == mode)
+    return;
   accessibility_mode_ = mode;
+  for (RenderProcessHost::iterator it(RenderProcessHost::AllHostsIterator());
+       !it.IsAtEnd(); it.Advance()) {
+    RenderProcessHost* render_process_host = it.GetCurrentValue();
+    DCHECK(render_process_host);
+
+    // Ignore processes that don't have a connection, such as crashed tabs.
+    if (!render_process_host->HasConnection())
+      continue;
+
+    RenderProcessHost::RenderWidgetHostsIterator rwit(

[sky, 2013/05/01 00:51:22]

nit: move into for loop (like you did on 131).

+        render_process_host->GetRenderWidgetHostsIterator());
+    for (; !rwit.IsAtEnd(); rwit.Advance()) {
+      RenderWidgetHost* rwh = const_cast<RenderWidgetHost*>(

[sky, 2013/05/01 00:51:22]

I'm not sure about the const_cast here.

[jam, 2013/05/01 05:19:17]

seems fine to me. i think it's a mistake that the iterator gives const pointers

+          rwit.GetCurrentValue());
+      DCHECK(rwh);
+      if (!rwh || !rwh->IsRenderView())
+        continue;
+      RenderWidgetHostImpl* rwhi = RenderWidgetHostImpl::From(rwh);
+      rwhi->SetAccessibilityMode(mode);
+    }
+  }
 }
 
 }  // namespace content