Media Stream Image Capture (4): wire takePhoto and implement in FakeVCDevice

content/browser/media/capture/image_capture_impl.cc

Index: content/browser/media/capture/image_capture_impl.cc
diff --git a/content/browser/media/capture/image_capture_impl.cc b/content/browser/media/capture/image_capture_impl.cc
index bfc8b0d0aec9be4af5c1e59d29aeb5512a03753b..1722a4f3a59c4622915872f4099bab3c91fc0e2d 100644
--- a/content/browser/media/capture/image_capture_impl.cc
+++ b/content/browser/media/capture/image_capture_impl.cc
@@ -5,10 +5,52 @@
 #include "content/browser/media/capture/image_capture_impl.h"
 
 #include "base/bind_helpers.h"
+#include "content/browser/browser_main_loop.h"
+#include "content/browser/renderer_host/media/media_stream_manager.h"
+#include "content/browser/renderer_host/media/video_capture_manager.h"
+#include "content/common/media/media_stream_options.h"
 #include "content/public/browser/browser_thread.h"
+#include "media/capture/video/video_capture_device.h"
 
 namespace content {
 
+namespace {
+
+void RunMojoCallback(const ImageCaptureImpl::TakePhotoCallback& callback,
+                     const std::string& mime_type,
+                     mojo::Array<uint8_t> data) {

[tommi (sloooow) - chröme, 2016/05/09 11:17:32]

just checking - this is moved and not copied, right? (have you verified?)

I'm not actually sure what happens in this case, but my gut instinct was that
the Array would be owned by the Bind() and therefore not moved when the callback
is made, but rather copied.  It would be a shame to have to copy the array
twice.

[mcasas, 2016/05/09 16:48:40]

Yeah, mojo::Array is a moveable-not-copyable type [1]
(and, for reference, mojo types ending in Ptr behave
like unique_ptrs).

[1]
https://code.google.com/p/chromium/codesearch#chromium/src/mojo/public/cpp/bi...

+  callback.Run(mime_type, std::move(data));
+}
+
+void RunTakePhotoCallback(const ImageCaptureImpl::TakePhotoCallback& callback,
+                          const std::string& mime_type,
+                          std::unique_ptr<std::vector<uint8_t>> data) {
+  DCHECK(data.get());
+  BrowserThread::PostTask(
+      BrowserThread::UI, FROM_HERE,
+      base::Bind(&RunMojoCallback, callback, mime_type,
+                 base::Passed(mojo::Array<uint8_t>::From(*data))));

[tommi (sloooow) - chröme, 2016/05/09 11:17:32]

if you find that the array is actually copied, consider just moving |data| here
and calling the From() method in the RunMojoCallback function.

[mcasas, 2016/05/09 16:48:40]

Acknowledged.

+}
+
+void TakePhotoOnIOThread(const mojo::String& source_id,
+                         const ImageCaptureImpl::TakePhotoCallback& callback,
+                         MediaStreamManager* media_stream_manager) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  const int session_id =
+      media_stream_manager->VideoDeviceIdToSessionId(source_id);
+
+  if (session_id == StreamDeviceInfo::kNoId ||
+      !media_stream_manager->video_capture_manager()->TakePhoto(
+          session_id, base::Bind(&RunTakePhotoCallback, callback))) {
+    std::unique_ptr<std::vector<uint8_t>> empty_vector(
+        new std::vector<uint8_t>());
+    RunTakePhotoCallback(callback, "", std::move(empty_vector));
+  }
+}
+
+}  // anonymous namespace
+
 // static
 void ImageCaptureImpl::Create(
     mojo::InterfaceRequest<blink::mojom::ImageCapture> request) {
@@ -18,13 +60,14 @@ void ImageCaptureImpl::Create(
 
 ImageCaptureImpl::~ImageCaptureImpl() {}
 
-void ImageCaptureImpl::TakePhoto(const mojo::String& /* source_id */,
+void ImageCaptureImpl::TakePhoto(const mojo::String& source_id,
                                  const TakePhotoCallback& callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-
-  // TODO(mcasas): Implement this feature., https://crbug.com/518807.
-  mojo::Array<uint8_t> data(1);
-  callback.Run("text/plain", std::move(data));
+  // media_stream_manager() can only be called on UI thread.
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&TakePhotoOnIOThread, source_id, callback,
+                 BrowserMainLoop::GetInstance()->media_stream_manager()));
 }
 
 ImageCaptureImpl::ImageCaptureImpl(