Tab Audio Mirroring: WebContentsAudioInputStream is a new implementation which represents the lifet…

content/browser/renderer_host/media/web_contents_capture_util.cc

 // 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/media/web_contents_capture_util.h"
 
 #include "base/basictypes.h"
+#include "base/message_loop_proxy.h"
 #include "base/string_number_conversions.h"
 #include "base/string_piece.h"
 #include "base/string_util.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/render_process_host.h"
+#include "content/public/browser/render_view_host.h"
+#include "content/public/browser/web_contents.h"
+
+namespace content {
 
 namespace {
 
 const char kVirtualDeviceScheme[] = "virtual-media-stream://";
 
 }  // namespace
 
-namespace content {
-
+// static
 std::string WebContentsCaptureUtil::AppendWebContentsDeviceScheme(
     const std::string& device_id) {
   return kVirtualDeviceScheme + device_id;
 }
 
+// static
 std::string WebContentsCaptureUtil::StripWebContentsDeviceScheme(
     const std::string& device_id) {
   return (IsWebContentsDeviceId(device_id) ?
               device_id.substr(arraysize(kVirtualDeviceScheme) - 1) :
               device_id);
 }
 
+// static
 bool WebContentsCaptureUtil::IsWebContentsDeviceId(
     const std::string& device_id) {
   return StartsWithASCII(device_id, kVirtualDeviceScheme, true);
 }
 
+// static
 bool WebContentsCaptureUtil::ExtractTabCaptureTarget(
     const std::string& device_id_param,
     int* render_process_id,
     int* render_view_id) {
   if (!IsWebContentsDeviceId(device_id_param))
     return false;
 
   const std::string device_id = device_id_param.substr(
       arraysize(kVirtualDeviceScheme) - 1);
 
   const size_t sep_pos = device_id.find(':');
   if (sep_pos == std::string::npos)
     return false;
 
   const base::StringPiece component1(device_id.data(), sep_pos);
   const base::StringPiece component2(device_id.data() + sep_pos + 1,
                                      device_id.length() - sep_pos - 1);
 
   return (base::StringToInt(component1, render_process_id) &&
           base::StringToInt(component2, render_view_id));
 }
 
+WebContentsTracker::WebContentsTracker() {}
+
+WebContentsTracker::~WebContentsTracker() {
+  DCHECK(!web_contents()) << "BUG: Still observering!";
+}
+
+void WebContentsTracker::Start(int render_process_id, int render_view_id,
+                               const ChangeCallback& callback) {
+  DCHECK(!message_loop_ || message_loop_->BelongsToCurrentThread());
+
+  message_loop_ = base::MessageLoopProxy::current();
+  DCHECK(message_loop_);
+  callback_ = callback;
+
+  BrowserThread::PostTask(
+      BrowserThread::UI, FROM_HERE,
+      base::Bind(&WebContentsTracker::LookUpAndObserveWebContents, this,
+                 render_process_id, render_view_id));
+}
+
+void WebContentsTracker::Stop() {
+  DCHECK(message_loop_->BelongsToCurrentThread());
+
+  callback_.Reset();
+
+  BrowserThread::PostTask(
+      BrowserThread::UI, FROM_HERE,
+      base::Bind(&WebContentsTracker::Observe, this,
+                 static_cast<WebContents*>(NULL)));
+}
+
+void WebContentsTracker::OnWebContentsChangeEvent() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  WebContents* const wc = web_contents();
+  RenderViewHost* const rvh = wc ? wc->GetRenderViewHost() : NULL;
+  RenderProcessHost* const rph = rvh ? rvh->GetProcess() : NULL;
+
+  const int render_process_id = rph ? rph->GetID() : MSG_ROUTING_NONE;
+  const int render_view_id = rvh ? rvh->GetRoutingID() : MSG_ROUTING_NONE;
+
+  message_loop_->PostTask(FROM_HERE,
+      base::Bind(&WebContentsTracker::MaybeDoCallback, this,
+                 render_process_id, render_view_id));
+}
+
+void WebContentsTracker::MaybeDoCallback(int render_process_id,
+                                         int render_view_id) {
+  DCHECK(message_loop_->BelongsToCurrentThread());
+
+  if (!callback_.is_null())
+    callback_.Run(render_process_id, render_view_id);
+}
+
+void WebContentsTracker::LookUpAndObserveWebContents(int render_process_id,
+                                                     int render_view_id) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  RenderViewHost* const rvh =
+      RenderViewHost::FromID(render_process_id, render_view_id);
+  DVLOG_IF(1, !rvh) << "RenderViewHost::FromID("
+                    << render_process_id << ", " << render_view_id
+                    << ") returned NULL.";
+  Observe(rvh ? WebContents::FromRenderViewHost(rvh) : NULL);
+  DVLOG_IF(1, !web_contents())
+      << "WebContents::FromRenderViewHost(" << rvh << ") returned NULL.";
+
+  OnWebContentsChangeEvent();
+}
+
+void WebContentsTracker::RenderViewReady() {
+  OnWebContentsChangeEvent();
+}
+
+void WebContentsTracker::AboutToNavigateRenderView(RenderViewHost* rvh) {
+  OnWebContentsChangeEvent();
+}
+
+void WebContentsTracker::DidNavigateMainFrame(
+    const LoadCommittedDetails& details, const FrameNavigateParams& params) {
+  OnWebContentsChangeEvent();
+}
+
+void WebContentsTracker::WebContentsDestroyed(WebContents* web_contents) {
+  OnWebContentsChangeEvent();
+}
+
 }  // namespace content