Implement screen capture for android

content/browser/media/capture/web_contents_video_capture_device.cc

Index: content/browser/media/capture/web_contents_video_capture_device.cc
diff --git a/content/browser/media/capture/web_contents_video_capture_device.cc b/content/browser/media/capture/web_contents_video_capture_device.cc
index 8380682fc5064f11b55813af04cb4549994a244e..5a855f5449e80a84b4d15aec3f3e04d82682f508 100644
--- a/content/browser/media/capture/web_contents_video_capture_device.cc
+++ b/content/browser/media/capture/web_contents_video_capture_device.cc
@@ -218,8 +218,9 @@ class WebContentsCaptureMachine : public VideoCaptureMachine {
   ~WebContentsCaptureMachine() override;
 
   // VideoCaptureMachine overrides.
-  bool Start(const scoped_refptr<ThreadSafeCaptureOracle>& oracle_proxy,
-             const media::VideoCaptureParams& params) override;
+  void Start(const scoped_refptr<ThreadSafeCaptureOracle>& oracle_proxy,
+             const media::VideoCaptureParams& params,
+             const base::Callback<void(bool)> callback) override;
   void Stop(const base::Closure& callback) override;
 
   // Starts a copy from the backing store or the composited surface. Must be run
@@ -233,6 +234,9 @@ class WebContentsCaptureMachine : public VideoCaptureMachine {
                    deliver_frame_cb);
 
  private:
+  bool InternalStart(const scoped_refptr<ThreadSafeCaptureOracle>& oracle_proxy,
+                     const media::VideoCaptureParams& params);
+  void InternalStop(const base::Closure& callback);
   bool IsStarted() const;
 
   // Computes the preferred size of the target RenderWidget for optimal capture.
@@ -482,7 +486,22 @@ bool WebContentsCaptureMachine::IsStarted() const {
   return weak_ptr_factory_.HasWeakPtrs();
 }
 
-bool WebContentsCaptureMachine::Start(
+void WebContentsCaptureMachine::Start(
+    const scoped_refptr<ThreadSafeCaptureOracle>& oracle_proxy,
+    const media::VideoCaptureParams& params,
+    const base::Callback<void(bool)> callback) {
+  // Starts the capture machine asynchronously.
+  BrowserThread::PostTaskAndReplyWithResult(
+      BrowserThread::UI,
+      FROM_HERE,
+      base::Bind(&WebContentsCaptureMachine::InternalStart,
+                 base::Unretained(this),
+                 oracle_proxy,
+                 params),
+      callback);
+}
+
+bool WebContentsCaptureMachine::InternalStart(
     const scoped_refptr<ThreadSafeCaptureOracle>& oracle_proxy,
     const media::VideoCaptureParams& params) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
@@ -509,6 +528,15 @@ bool WebContentsCaptureMachine::Start(
 }
 
 void WebContentsCaptureMachine::Stop(const base::Closure& callback) {
+  // Stops the capture machine asynchronously.
+  BrowserThread::PostTask(
+      BrowserThread::UI, FROM_HERE, base::Bind(
+          &WebContentsCaptureMachine::InternalStop,
+          base::Unretained(this),
+          callback));
+}
+
+void WebContentsCaptureMachine::InternalStop(const base::Closure& callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   if (!IsStarted()) {