Defect 248426: Speak rendered text when no selection is made on Mac

content/browser/renderer_host/render_widget_host_view_mac.mm

 // Copyright (c) 2012 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/renderer_host/render_widget_host_view_mac.h"
 
 #import <objc/runtime.h>
 #include <OpenGL/gl.h>
 #include <QuartzCore/QuartzCore.h>
 
@@ skipping 636 matching lines @@
   DestroyCompositedIOSurfaceLayer(kRemoveLayerFromHierarchy);
   compositing_iosurface_ = NULL;
   compositing_iosurface_context_ = NULL;
 }
 
 bool RenderWidgetHostViewMac::OnMessageReceived(const IPC::Message& message) {
   bool handled = true;
   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;
 }
 
 void RenderWidgetHostViewMac::InitAsChild(
     gfx::NativeView parent_view) {
 }
 
 void RenderWidgetHostViewMac::InitAsPopup(
@@ skipping 406 matching lines @@
     [cocoa_view_ setToolTipAtMousePoint:tooltip_nsstring];
   }
 }
 
 bool RenderWidgetHostViewMac::SupportsSpeech() const {
   return [NSApp respondsToSelector:@selector(speakString:)] &&
          [NSApp respondsToSelector:@selector(stopSpeaking:)];
 }
 
 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 {
   return [NSApp respondsToSelector:@selector(isSpeaking)] &&
          [NSApp isSpeaking];
 }
 
 void RenderWidgetHostViewMac::StopSpeaking() {
   if ([NSApp respondsToSelector:@selector(stopSpeaking:)])
     [NSApp stopSpeaking:cocoa_view_];
@@ skipping 999 matching lines @@
 
 void RenderWidgetHostViewMac::OnPluginFocusChanged(bool focused,
                                                    int plugin_id) {
   [cocoa_view_ pluginFocusChanged:(focused ? YES : NO) forPlugin:plugin_id];
 }
 
 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;
   src_gl_subrect.set_y(GetViewBounds().height() - rect.bottom());
 
   return gfx::ToEnclosingRect(gfx::ScaleRect(src_gl_subrect,
                                              ViewScaleFactor()));
 }
 
 void RenderWidgetHostViewMac::AddPendingLatencyInfo(
@@ skipping 1861 matching lines @@
 
 // "-webkit-app-region: drag | no-drag" is implemented on Mac by excluding
 // regions that are not draggable. (See ControlRegionView in
 // native_app_window_cocoa.mm). This requires the render host view to be
 // draggable by default.
 - (BOOL)mouseDownCanMoveWindow {
   return YES;
 }
 
 @end