Convert app banners to use Mojo.

third_party/WebKit/Source/web/WebLocalFrameImpl.cpp

Index: third_party/WebKit/Source/web/WebLocalFrameImpl.cpp
diff --git a/third_party/WebKit/Source/web/WebLocalFrameImpl.cpp b/third_party/WebKit/Source/web/WebLocalFrameImpl.cpp
index 2c3891b0241afdff6d33ae526e37e046c29b42e1..59b0573153b1c48dd4e2b8be4ff348ba822495e3 100644
--- a/third_party/WebKit/Source/web/WebLocalFrameImpl.cpp
+++ b/third_party/WebKit/Source/web/WebLocalFrameImpl.cpp
@@ -177,6 +177,7 @@
 #include "platform/weborigin/SchemeRegistry.h"
 #include "platform/weborigin/SecurityPolicy.h"
 #include "public/platform/InterfaceProvider.h"
+#include "public/platform/InterfaceRegistry.h"
 #include "public/platform/WebDoubleSize.h"
 #include "public/platform/WebFloatPoint.h"
 #include "public/platform/WebFloatRect.h"
@@ -228,6 +229,7 @@
 #include "wtf/PtrUtil.h"
 #include <algorithm>
 #include <memory>
+#include <utility>
 
 namespace blink {
 
@@ -1614,11 +1616,16 @@ void WebLocalFrameImpl::initializeCoreFrame(FrameHost* host,
   // during init(). Note that this may dispatch JS events; the frame may be
   // detached after init() returns.
   frame()->init();
-  if (frame() &&
-      frame()->loader().stateMachine()->isDisplayingInitialEmptyDocument() &&
-      !parent() && !opener() &&
-      frame()->settings()->shouldReuseGlobalForUnownedMainFrame())
-    frame()->document()->getSecurityOrigin()->grantUniversalAccess();
+  if (frame()) {
+    if (frame()->loader().stateMachine()->isDisplayingInitialEmptyDocument() &&
+        !parent() && !opener() &&
+        frame()->settings()->shouldReuseGlobalForUnownedMainFrame()) {
+      frame()->document()->getSecurityOrigin()->grantUniversalAccess();
+    }
+
+    frame()->interfaceRegistry()->addInterface(
+        WTF::bind(&AppBannerController::create, wrapPersistent(frame())));

[haraken, 2016/10/20 15:51:23]

I'm just curious but why does addInterface take a WTF::Function instead of the
created InterfacePtr?

[dominickn, 2016/10/20 23:41:18]

addInterface registers a WTF::Function(request) callback to be run when it
receives a request of the type expected by the callback. When you call
addInterface, you don't have an InterfaceRequest (InterfacePtr is the "other
end" of the Mojo pipe; when you register an interface the callback expects an
InterfaceRequest). All you're doing in addInterface is saying, "run this
callback when you receive that type of request".

AppBannerController::create is bound with the frame and expects one additional
argument, which is a mojo::InterfaceRequest<AppBannerClient>. When that request
comes in (via the AppBannerManager calling SendBannerPromptRequest), the
WTF::Function is invoked to lazily create an AppBannerController, passing in the
InterfaceRequest.

[haraken, 2016/10/21 08:59:45]

Sorry for being noisy, but where is the expected request type specified?
addInterface just takes a WTF::Function and it doesn't know when to invoke the
function.

[dominickn, 2016/10/21 12:26:57]

The short answer is template magic. :)

The long answer is that the WTF::Function must have an
InterfaceRequest<Interface> parameter in its signature (see
AppBannerController:bindMojoRequest). The Interface template class is the
generated mojo interface class, which is blink::mojom::AppBannerController in
this case. Mojo always injects a static, unique Name_ member into the generated
classes; addInterface simply maps blink::mojom::AppBannerController::Name_ to
the WTF::Function which is passed in.

So now we query the interface registry. That passes in an
InterfaceRequest<blink::mojom::AppBannerController>, so the registry just looks
up whether there is a WTF::Function mapped to
blink::mojom::AppBannerController::Name_, and runs it passing the request. This
creates a concrete AppBannerController and binds the pipe, allowing the other
end of the pipe to call methods on the AppBannerController. This is mostly
implemented inside the services / mojo layer and is pretty much all
automatically generated. Does that make sense?

If you're interested, the actual impl is
https://cs.chromium.org/chromium/src/services/service_manager/public/cpp/inte...
and
https://cs.chromium.org/chromium/src/services/service_manager/public/cpp/lib/...

[haraken, 2016/10/23 22:42:15]

Thanks, makes sense.

I'd personally prefer a more explicit binding API but delegate the decision to
Mojo experts :)

+  }
 }
 
 LocalFrame* WebLocalFrameImpl::createChildFrame(
@@ -2089,17 +2096,6 @@ void WebLocalFrameImpl::sendOrientationChangeEvent() {
     frame()->localDOMWindow()->sendOrientationChangeEvent();
 }
 
-void WebLocalFrameImpl::willShowInstallBannerPrompt(
-    int requestId,
-    const WebVector<WebString>& platforms,
-    WebAppBannerPromptReply* reply) {
-  if (!frame())
-    return;
-
-  AppBannerController::willShowInstallBannerPrompt(
-      requestId, client()->appBannerClient(), frame(), platforms, reply);
-}
-
 void WebLocalFrameImpl::requestRunTask(WebSuspendableTask* task) const {
   DCHECK(frame());
   DCHECK(frame()->document());