Make Edit>Speech>Speak Selection work for PDFs on Mac

content/browser/renderer_host/render_widget_host_view_mac.mm

Index: content/browser/renderer_host/render_widget_host_view_mac.mm
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.mm b/content/browser/renderer_host/render_widget_host_view_mac.mm
index b767f463fe3ca418e5fe52e2b215d30df5eb162f..3877ad0340fb8b5591e49a47351398a7d1d848e4 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac.mm
@@ -47,6 +47,8 @@
 #include "content/common/input_messages.h"
 #include "content/common/view_messages.h"
 #include "content/common/webplugin_geometry.h"
+#include "content/public/browser/browser_context.h"
+#include "content/public/browser/browser_plugin_guest_manager.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/native_web_keyboard_event.h"
 #include "content/public/browser/notification_service.h"
@@ -107,6 +109,23 @@ BOOL EventIsReservedBySystem(NSEvent* event) {
   return helper->map()->IsEventReserved(event);
 }
 
+RenderWidgetHostViewMac* GetRenderWidgetHostViewToUse(
+    RenderWidgetHostViewMac* render_widget_host_view) {
+  WebContents* web_contents = render_widget_host_view->GetWebContents();
+  if (!web_contents)
+    return render_widget_host_view;
+  content::BrowserPluginGuestManager* guest_manager =
+      web_contents->GetBrowserContext()->GetGuestManager();
+  if (!guest_manager)
+    return render_widget_host_view;
+  content::WebContents* guest =
+      guest_manager->GetFullPageGuest(web_contents);
+  if (!guest)
+    return render_widget_host_view;
+  return static_cast<RenderWidgetHostViewMac*>(
+      guest->GetRenderWidgetHostView());
+}
+
 }  // namespace
 
 // These are not documented, so use only after checking -respondsToSelector:.
@@ -3282,11 +3301,11 @@ extern NSString *NSTextInputReplacementRangeAttributeName;
 }
 
 - (void)startSpeaking:(id)sender {
-  renderWidgetHostView_->SpeakSelection();
+  GetRenderWidgetHostViewToUse(renderWidgetHostView_.get())->SpeakSelection();
 }
 
 - (void)stopSpeaking:(id)sender {
-  renderWidgetHostView_->StopSpeaking();
+  GetRenderWidgetHostViewToUse(renderWidgetHostView_.get())->StopSpeaking();
 }
 
 - (void)cancelComposition {