Expose the capturePicture feature in RenderView for Android WebView legacy API support.

content/renderer/render_view_impl.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/renderer/render_view_impl.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/bind.h"
@@ skipping 6560 matching lines @@
   return true;
 }
 #endif
 
 void RenderViewImpl::OnReleaseDisambiguationPopupDIB(
     TransportDIB::Handle dib_handle) {
   TransportDIB* dib = TransportDIB::CreateWithHandle(dib_handle);
   RenderProcess::current()->ReleaseTransportDIB(dib);
 }
 
+#if defined(OS_ANDROID)
+void RenderViewImpl::SetCapturePictureCallback(
+    const CapturePictureCallback& callback) {
+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kEnableWebViewCapturePictureAPI))
+    capture_picture_callback_ = callback;
+}
+
+skia::RefPtr<SkPicture> RenderViewImpl::CapturePicture() {
+  return web_layer_tree_view_ && CommandLine::ForCurrentProcess()->HasSwitch(

[Leandro Graciá Gil, 2013/01/11 13:11:33]

This patch depends on https://codereview.chromium.org/11575049/ landing
successfully and introducing web_layer_tree_view_ in RenderWidget.

+      switches::kEnableWebViewCapturePictureAPI) ?
+          web_layer_tree_view_->capturePicture() :
+          skia::RefPtr<SkPicture>();
+}
+
+void RenderViewImpl::didBecomeReadyForAdditionalInput() {

[joth, 2013/01/11 21:41:17]

I propose we should separate out the two different primitives here, and extract
upwards a lot of the policy decisions into the embedder and out of content/ as a
result:

1/ Here, we just push  a new notification to RV observers:-
FOR_EACH_OBSERVER(RenderViewObserver, observers_,
DidBecomeReadyForAdditionalInput();
i.e. this can be done unconditionally, regardless of OS_ANDROID or any funky
command line switch.

2/ We add the RenderViewImpl::CapturePicture() as you have it above, but as it's
not (of itself) spontaneous doing anything at all I'd argue a command line
switch is not needed. Just a warning on the function that it's not necessarily
"free" to call, and perhaps we also keep it under OS_ANDROID.

3/ The RenderViewImpl::SetCapturePictureCallback can be removed entirely. We
just implement that logic (receiving DidBecomeReadyForAdditionalInput
notifications and calling CapturePicture() if appropriate) up in the
anroid_webview layer.

[jamesr, 2013/01/11 21:53:26]

why are you hooking on didBecomeReadyForAdditionalInput()? this operation
doesn't have anything to do with input event throttling

[Leandro Graciá Gil, 2013/01/12 00:26:09]

The intention is to trigger the callback on every new frame contents. This is
supposed to be called on didCommit by the WebKit side, isn't it? That's what
enne and nduca suggested us (if I interpreted it right).

Following Joth's suggestion, is there anything that we could use already exposed
to RenderViewObservers?

+  RenderWidget::didBecomeReadyForAdditionalInput();
+  if (web_layer_tree_view_ && !capture_picture_callback_.is_null())
+      capture_picture_callback_.Run(web_layer_tree_view_->capturePicture());
+}
+#endif
+
 }  // namespace content