Implement web speech synthesis.

content/browser/renderer_host/render_process_host_impl.cc

Index: content/browser/renderer_host/render_process_host_impl.cc
diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
index 777e5acaf63f9a7ba09abbee6242df4569d2c325..4b7ce487316e861761f526256ed9ca1e311366be 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -88,6 +88,7 @@
 #include "content/browser/storage_partition_impl.h"
 #include "content/browser/speech/input_tag_speech_dispatcher_host.h"
 #include "content/browser/speech/speech_recognition_dispatcher_host.h"
+#include "content/browser/speech/tts_dispatcher_host_impl.h"
 #include "content/browser/tracing/trace_message_filter.h"
 #include "content/browser/webui/web_ui_controller_factory_registry.h"
 #include "content/browser/worker_host/worker_storage_partition.h"
@@ -637,6 +638,7 @@ void RenderProcessHostImpl::CreateMessageFilters() {
   channel_->AddFilter(new ProfilerMessageFilter(PROCESS_TYPE_RENDERER));
   channel_->AddFilter(new HistogramMessageFilter());
   channel_->AddFilter(new HyphenatorMessageFilter(this));
+  channel_->AddFilter(new TtsDispatcherHostImpl(GetID(), GetBrowserContext()));
 }
 
 int RenderProcessHostImpl::GetNextRoutingID() {