Make WebTestProxy handle printing + compositing mode

content/shell/renderer/test_runner/WebTestProxy.cpp

Index: content/shell/renderer/test_runner/WebTestProxy.cpp
diff --git a/content/shell/renderer/test_runner/WebTestProxy.cpp b/content/shell/renderer/test_runner/WebTestProxy.cpp
index 1a85a23b2410dd473717fe5ffa159fb858939355..1085be8b2bb691fac6f4485df0adb3a421c911eb 100644
--- a/content/shell/renderer/test_runner/WebTestProxy.cpp
+++ b/content/shell/renderer/test_runner/WebTestProxy.cpp
@@ -499,6 +499,18 @@ void WebTestProxyBase::CapturePixelsAsync(
 
   DCHECK(webWidget()->isAcceleratedCompositingActive());
   DCHECK(!callback.is_null());
+
+  if (m_testInterfaces->testRunner()->isPrinting()) {
+    // TODO(enne): get rid of stateful canvas().
+    webWidget()->layout();
+    paintPagesWithBoundaries();
+    DrawSelectionRect(canvas());
+    SkBaseDevice* device = skia::GetTopDevice(*canvas());
+    const SkBitmap& bitmap = device->accessBitmap(false);
+    callback.Run(bitmap);

[danakj, 2014/05/09 21:17:21]

do you wanna post-task this to keep it async? otherwise printing tests get
somewhat different call stacks?

[enne (OOO), 2014/05/09 21:25:06]

It's a nice thought, but it seems awkward to do with the canvas() being stored
statefully since something else could clobber it in the meantime.  I could make
a copy of the bitmap and then pass that along with the callback, but that seems
wasteful.

Can you think of an ok way to do this?

[danakj, 2014/05/09 21:37:25]

I figured the test harness shouldn't be doing anything else in the meantime so
it should "just work". If that's not true then things are indeed more awkward
until that happens. Alternatively you could post-task this whole block here to
keep it async until the m_canvas can go?

[enne (OOO), 2014/05/09 22:03:20]

Done.

+    return;
+  }
+
   m_compositeAndReadbackCallbacks.push_back(callback);
   webWidget()->compositeAndReadbackAsync(this);
 }