[dom_distiller] Add support for incremental viewer.

components/dom_distiller/core/fake_distiller.cc

Index: components/dom_distiller/core/fake_distiller.cc
diff --git a/components/dom_distiller/core/fake_distiller.cc b/components/dom_distiller/core/fake_distiller.cc
index bb5ef92b37bbb1dc4efd365dcd8fdfd03fa3114f..8211032fc9f08af8adfe55ab6d338e8c06a78f66 100644
--- a/components/dom_distiller/core/fake_distiller.cc
+++ b/components/dom_distiller/core/fake_distiller.cc
@@ -6,6 +6,7 @@
 
 #include "base/auto_reset.h"
 #include "base/bind.h"
+#include "base/callback_helpers.h"
 #include "base/message_loop/message_loop.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -21,6 +22,15 @@ FakeDistiller::FakeDistiller(bool execute_callback)
   EXPECT_CALL(*this, Die()).Times(testing::AnyNumber());
 }
 
+FakeDistiller::FakeDistiller(
+    bool execute_callback,
+    const base::Closure& distillation_initiated_callback)
+    : execute_callback_(execute_callback),
+      destruction_allowed_(true),
+      distillation_initiated_callback_(distillation_initiated_callback) {
+  EXPECT_CALL(*this, Die()).Times(testing::AnyNumber());
+}
+
 FakeDistiller::~FakeDistiller() {
   EXPECT_TRUE(destruction_allowed_);
   Die();
@@ -34,6 +44,9 @@ void FakeDistiller::DistillPage(
   url_ = url;
   article_callback_ = article_callback;
   page_callback_ = page_callback;
+  if (!distillation_initiated_callback_.is_null()) {
+    base::ResetAndReturn(&distillation_initiated_callback_).Run();
+  }
   if (execute_callback_) {
     scoped_ptr<DistilledArticleProto> proto(new DistilledArticleProto);
     proto->add_pages()->set_url(url_.spec());
@@ -49,6 +62,12 @@ void FakeDistiller::RunDistillerCallback(
   PostDistillerCallback(proto.Pass());
 }
 
+void FakeDistiller::RunDistillerUpdateCallback(
+    const ArticleDistillationUpdate& update) {
+  page_callback_.Run(update);
+}
+
+
 void FakeDistiller::PostDistillerCallback(
     scoped_ptr<DistilledArticleProto> proto) {
   base::MessageLoop::current()->PostTask(