Add 'NavigationHandle::QueueConsoleMessage'.

content/browser/frame_host/navigation_handle_impl.h

Index: content/browser/frame_host/navigation_handle_impl.h
diff --git a/content/browser/frame_host/navigation_handle_impl.h b/content/browser/frame_host/navigation_handle_impl.h
index b212b3ee7a7a0c3ac01fca8a1175370a26b99844..cee91f31cdf1f0d79ff1177eef38553dca8430a4 100644
--- a/content/browser/frame_host/navigation_handle_impl.h
+++ b/content/browser/frame_host/navigation_handle_impl.h
@@ -18,6 +18,7 @@
 #include "content/common/content_export.h"
 #include "content/public/browser/navigation_data.h"
 #include "content/public/browser/navigation_throttle.h"
+#include "content/public/common/console_message_level.h"
 #include "url/gurl.h"
 
 struct FrameHostMsg_DidCommitProvisionalLoad_Params;
@@ -103,6 +104,8 @@ class CONTENT_EXPORT NavigationHandleImpl : public NavigationHandle {
   void Resume() override;
   void CancelDeferredNavigation(
       NavigationThrottle::ThrottleCheckResult result) override;
+  void QueueConsoleMessage(ConsoleMessageLevel level,
+                           const std::string& message) override;
   void RegisterThrottleForTesting(
       std::unique_ptr<NavigationThrottle> navigation_throttle) override;
   NavigationThrottle::ThrottleCheckResult CallWillStartRequestForTesting(
@@ -267,6 +270,12 @@ class CONTENT_EXPORT NavigationHandleImpl : public NavigationHandle {
   // end of a round of NavigationThrottleChecks.
   void RunCompleteCallback(NavigationThrottle::ThrottleCheckResult result);
 
+  // Outputs the messages in |console_queue_| to the relevant RenderFrameHost,
+  // in FIFO order. This method must be called after a response has been
+  // delivered for processing, and will clear out |console_queue_| as a side
+  // effect of sending the messages.
+  virtual void DumpMessagesToConsole();
+
   // Used in tests.
   State state() const { return state_; }
 
@@ -326,6 +335,9 @@ class CONTENT_EXPORT NavigationHandleImpl : public NavigationHandle {
   // Embedder data tied to this navigation.
   std::unique_ptr<NavigationData> navigation_data_;
 
+  // A queue of messages to be delivered to the devtools console upon commit.
+  std::queue<std::pair<ConsoleMessageLevel, const std::string>> console_queue_;
+
   DISALLOW_COPY_AND_ASSIGN(NavigationHandleImpl);
 };