Mojo framework for AndroidOverlay.

content/browser/gpu/gpu_process_host.cc

Index: content/browser/gpu/gpu_process_host.cc
diff --git a/content/browser/gpu/gpu_process_host.cc b/content/browser/gpu/gpu_process_host.cc
index 4aabfd167311f7e7bd0ab2e5047601a811a3685a..659c6f5effaeb31c6e8739b1284958a0236ca549 100644
--- a/content/browser/gpu/gpu_process_host.cc
+++ b/content/browser/gpu/gpu_process_host.cc
@@ -75,6 +75,9 @@
 
 #if defined(OS_ANDROID)
 #include "base/android/build_info.h"
+#include "content/public/browser/android/java_interfaces.h"
+#include "media/mojo/interfaces/android_overlay.mojom.h"
+#include "services/service_manager/public/cpp/interface_registry.h"
 #endif
 
 #if defined(OS_WIN)
@@ -318,6 +321,23 @@ void HostLoadedShader(int host_id,
 
 }  // anonymous namespace
 
+#if defined(OS_ANDROID)
+template <typename InterfaceType>
+void AddUIInterfaceHelper(service_manager::InterfaceRegistry* registry) {

[boliu, 2017/02/16 22:24:19]

Hmm, I don't know mojo at all.. my immediate question here is what's the
lifetime and thread safety guarantees of registry here.

Plus this class is all on the IO thread, can this be done somewhere else? Maybe
GpuProcessHostUIShim?

[liberato (no reviews please), 2017/02/17 17:47:12]

(fixed per rockot@'s suggestions.)

+  registry->AddInterface(
+      content::GetGlobalJavaInterfaces()
+          ->CreateInterfaceFactory<InterfaceType>(),
+      BrowserThread::GetTaskRunnerForThread(BrowserThread::UI));
+}
+
+template <typename InterfaceType>
+void AddUIInterface(service_manager::InterfaceRegistry* registry) {
+  BrowserThread::GetTaskRunnerForThread(BrowserThread::UI)
+      ->PostTask(FROM_HERE,
+                 base::Bind(&AddUIInterfaceHelper<InterfaceType>, registry));

[Ken Rockot(use gerrit already), 2017/02/17 06:29:56]

This is not safe, and CreateInterfaceFactory() while convenient is unfortunately
not sufficient for this case. |registry| lives on the IO thread where the
ConnectionFilter lives, so you can't just post to the UI thread to register a
binder on it there. Instead, you want to register a binder on the IO thread
which itself posts to the UI thread to handle each individual request, like so:

template <typename Interface>
void BindJavaInterface(mojo::InterfaceRequest<Interface> request) {
  DCHECK(/* on the UI thread */);
  content::GetGlobalJavaInterfaces()->GetInterface(std::move(request));
}

template <typename Interface>
void BindJavaInterfaceOnUIThread(mojo::InterfaceRequest<Interface> request) {
  BrowserThread::GetTaskRunnerForThread(BrowserThread::UI)->PostTask(
      FROM_HERE, base::Bind(&BindJavaInterface<Interface>,
base::Passed(&request));
}

/// ... in OnConnect

registry->AddInterface(base::Bind(
    &BindJavaInterfaceOnUIThread<media::mojom::AndroidOverlayProvider>));

[liberato (no reviews please), 2017/02/17 17:47:12]

thank you very much!

+}
+#endif
+
 class GpuProcessHost::ConnectionFilterImpl : public ConnectionFilter {
  public:
   ConnectionFilterImpl(GpuProcessHost* host) : host_(host) {}
@@ -332,6 +352,11 @@ class GpuProcessHost::ConnectionFilterImpl : public ConnectionFilter {
 
     GetContentClient()->browser()->ExposeInterfacesToGpuProcess(registry,
                                                                 host_);
+
+#if defined(OS_ANDROID)
+    AddUIInterface<media::mojom::AndroidOverlayProvider>(registry);
+#endif
+
     return true;
   }