Allow Chrome to bind an Application request from mojo_runner.

chrome/browser/chrome_browser_main.cc

Index: chrome/browser/chrome_browser_main.cc
diff --git a/chrome/browser/chrome_browser_main.cc b/chrome/browser/chrome_browser_main.cc
index 372d0ee473b064461c7dffada6a2ed778f297df8..8d8a4ce9351b11a5297ae825ad2b743b82667ddd 100644
--- a/chrome/browser/chrome_browser_main.cc
+++ b/chrome/browser/chrome_browser_main.cc
@@ -63,6 +63,7 @@
 #include "chrome/browser/memory/tab_manager.h"
 #include "chrome/browser/metrics/field_trial_synchronizer.h"
 #include "chrome/browser/metrics/thread_watcher.h"
+#include "chrome/browser/mojo_runner_util.h"
 #include "chrome/browser/nacl_host/nacl_browser_delegate_impl.h"
 #include "chrome/browser/net/crl_set_fetcher.h"
 #include "chrome/browser/performance_monitor/performance_monitor.h"
@@ -247,6 +248,12 @@
 #include "components/webusb/webusb_detector.h"
 #endif
 
+#if defined(MOJO_RUNNER_CLIENT)
+#include "mojo/application/public/cpp/application_delegate.h"
+#include "mojo/application/public/cpp/application_impl.h"
+#include "mojo/runner/child/runner_connection.h"
+#endif
+
 using content::BrowserThread;
 
 namespace {
@@ -571,6 +578,32 @@ const char kMissingLocaleDataMessage[] =
 
 }  // namespace chrome_browser
 
+#if defined(MOJO_RUNNER_CLIENT)
+class ChromeApplicationDelegate : public mojo::ApplicationDelegate {
+ public:
+  ChromeApplicationDelegate() {}
+  ~ChromeApplicationDelegate() override {}
+
+  // Runs the current thread's message loop until we receive an Initialize()
+  // call from the shell.
+  void RunUntilInitialize() {
+    base::MessageLoop::current()->Run();

[sky, 2015/11/05 00:29:34]

You sure you want to run a nested message loop here? The down side of doing a
message loop is you run the risk of pumping events you don't want to run at this
point. I wonder if it would be better to move this onto a dedicated thread and
wait on a mutex here.

Either way, I think it would be better to isolate all this code (this class and
the new code below) into a single class that is owned by ChromeBrowserMain. Less
ifdefs then.

+  }
+
+ private:
+  void Initialize(mojo::ApplicationImpl* application) override {
+    // TODO(beng): Connect to the window manager.
+    base::MessageLoop::current()->QuitNow();
+  }
+  bool ConfigureIncomingConnection(
+      mojo::ApplicationConnection* connection) override {
+    return false;
+  }
+
+  DISALLOW_COPY_AND_ASSIGN(ChromeApplicationDelegate);
+};
+#endif  // defined(MOJO_RUNNER_CLIENT)
+
 // BrowserMainParts ------------------------------------------------------------
 
 ChromeBrowserMainParts::ChromeBrowserMainParts(
@@ -1212,6 +1245,21 @@ int ChromeBrowserMainParts::PreMainMessageLoopRunImpl() {
   SCOPED_UMA_HISTOGRAM_LONG_TIMER("Startup.PreMainMessageLoopRunImplLongTime");
   const base::TimeTicks start_time_step1 = base::TimeTicks::Now();
 
+#if defined(MOJO_RUNNER_CLIENT)
+  if (chrome::IsRunningInMojoRunner()) {
+    // When run from the Mojo Runner, block until we can bind an Application
+    // request from the runner's shell, and run the main message loop until
+    // our bound ApplicationImpl is ready to use.
+    mojo::InterfaceRequest<mojo::Application> application_request;
+    runner_connection_.reset(
+        mojo::runner::RunnerConnection::ConnectToRunner(&application_request));
+    application_delegate_.reset(new ChromeApplicationDelegate);
+    application_impl_.reset(new mojo::ApplicationImpl(
+        application_delegate_.get(), application_request.Pass()));
+    application_delegate_->RunUntilInitialize();
+  }
+#endif  // defined(MOJO_RUNNER_CLIENT)
+
 #if defined(OS_WIN)
   // Windows parental controls calls can be slow, so we do an early init here
   // that calculates this value off of the UI thread.