Don't start a second pre-render if one is in progress.

components/offline_pages/background/request_coordinator_unittest.cc

Index: components/offline_pages/background/request_coordinator_unittest.cc
diff --git a/components/offline_pages/background/request_coordinator_unittest.cc b/components/offline_pages/background/request_coordinator_unittest.cc
index ebcbe140f39a7b3f1a30b8ffbf8e619d52ed20f4..cda7460f99c70a5fcce754f9203025beed355085 100644
--- a/components/offline_pages/background/request_coordinator_unittest.cc
+++ b/components/offline_pages/background/request_coordinator_unittest.cc
@@ -10,6 +10,7 @@
 
 #include "base/bind.h"
 #include "base/location.h"
+#include "base/logging.h"
 #include "base/test/test_simple_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "components/offline_pages/background/device_conditions.h"
@@ -92,6 +93,14 @@ class RequestCoordinatorTest
     return coordinator_.get();
   }
 
+  bool request_in_progress() {
+    return coordinator_->is_busy();
+  }
+
+  void SendRequestToOffliner(SavePageRequest& request) {
+    coordinator_->SendRequestToOffliner(request);
+  }
+
   // Empty callback function
   void EmptyCallbackFunction(bool result) {
   }
@@ -175,6 +184,23 @@ TEST_F(RequestCoordinatorTest, StartProcessingWithNoRequests) {
   EXPECT_TRUE(coordinator()->StartProcessing(device_conditions, callback));
 }
 
+TEST_F(RequestCoordinatorTest, StartProcessingWithRequestInProgress) {
+  // Build a request.
+  offline_pages::SavePageRequest request(
+      kRequestId, kUrl, kClientId, base::Time::Now());
+  // Sending the request to the offliner should make it busy.
+  SendRequestToOffliner(request);
+  EXPECT_TRUE(request_in_progress());
+  // Now trying to start processing on another request should return false.
+  DeviceConditions device_conditions(false, 75,
+                                     net::NetworkChangeNotifier::CONNECTION_3G);
+  base::Callback<void(bool)> callback =
+      base::Bind(
+          &RequestCoordinatorTest::EmptyCallbackFunction,
+          base::Unretained(this));
+  EXPECT_FALSE(coordinator()->StartProcessing(device_conditions, callback));
+}
+
 TEST_F(RequestCoordinatorTest, SavePageLater) {
   EXPECT_TRUE(coordinator()->SavePageLater(kUrl, kClientId));