Defect 248426: Speak rendered text when no selection is made 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 34ff9bff0c4c67ba9027a346fffa47bac8f3e303..e19b656501ebe9aee2c1f319a9b93f4f2c1523dd 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac.mm
@@ -654,6 +654,8 @@ bool RenderWidgetHostViewMac::OnMessageReceived(const IPC::Message& message) {
   IPC_BEGIN_MESSAGE_MAP(RenderWidgetHostViewMac, message)
     IPC_MESSAGE_HANDLER(ViewHostMsg_PluginFocusChanged, OnPluginFocusChanged)
     IPC_MESSAGE_HANDLER(ViewHostMsg_StartPluginIme, OnStartPluginIme)
+    IPC_MESSAGE_HANDLER(ViewMsg_GetRenderedTextCompleted,
+        OnGetRenderedTextCompleted)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
   return handled;
@@ -1080,8 +1082,17 @@ bool RenderWidgetHostViewMac::SupportsSpeech() const {
 }
 
 void RenderWidgetHostViewMac::SpeakSelection() {
-  if ([NSApp respondsToSelector:@selector(speakString:)])
-    [NSApp speakString:base::SysUTF8ToNSString(selected_text_)];
+  if (![NSApp respondsToSelector:@selector(speakString:)])
+    return;
+
+  if (selected_text_.empty() && render_widget_host_) {
+    // Route an IPC message to get content as text for a web contents.

[jeremy, 2014/06/29 11:38:55]

Needs better comment, how about:
// If there's no selection, speak all text. In this case, send an asynchronous
request for all the text in the webcontents. ViewMsg_GetRenderedTextCompleted is
sent back on completion.

+    render_widget_host_->Send(new ViewMsg_GetRenderedText(
+        render_widget_host_->GetRoutingID()));
+    return;
+  }
+
+  [NSApp speakString:base::SysUTF8ToNSString(selected_text_)];

[jeremy, 2014/06/29 11:38:55]

My preference would be to have this moved to a private method - e.g. SpeakText()
and then call that both from here and OnGetRenderedTextCompleted().

 }
 
 bool RenderWidgetHostViewMac::IsSpeaking() const {
@@ -2101,6 +2112,15 @@ void RenderWidgetHostViewMac::OnStartPluginIme() {
   [cocoa_view_ setPluginImeActive:YES];
 }
 
+void RenderWidgetHostViewMac::OnGetRenderedTextCompleted(
+    const std::string& text) {
+  // Let TTS speak the text returned from call back
+  if (text.empty())
+    return;

[jeremy, 2014/06/29 11:38:55]

Just thinking out loud - are we ok with a browser issuing multiple TTS request
to a renderer when one is already in flight.
i.e. I request a "speak all text" command, renderer takes a while to respond,
then I do it again and I have 2 queued up. Does it make sense to drop any new
TTS commands on the floor for a webview if one is already in progress?

[sarka, 2014/06/30 16:10:30]

While TTS is in progress if another request is made then it all starts over.
This use case is analogous to Safari. I am not sure if TTS itself does these
kind of checks or perhaps at any given point only one request exists in the
queue. 

+
+  [NSApp speakString:base::SysUTF8ToNSString(text)];
+}
+
 gfx::Rect RenderWidgetHostViewMac::GetScaledOpenGLPixelRect(
     const gfx::Rect& rect) {
   gfx::Rect src_gl_subrect = rect;