<webview>: Implement fullscreen permission for html5 element.requestFullscreen()

We do it in two stages, first a DOM element requests fullscreen inside <webview>,
this fires a permissionrequest to the embedder of <webview> to decide
whether to allow/deny the request. The element goes fullscreen within
the <webview>'s bounds at this point.
The embedder can:
a) allow the request: in this case we perform the second stage, where the
<webview> element in the embedder enters fullscreen (provided that
the embedder has permission to enter fullscreen).
b) deny the request: in this case, <webview> exits fullscreen mode.

Note that b) will cause a flicker and blink interface is required to avoid that.
That is tracked on http://crbug.com/466854.

BUG=141198
Test=
Load a chrome app with a <webview> in it, make the <webview> point to
some site that has html5 fullscreen request, e.g. youtube.com.

Add an event listener in the chrome app so that it allows <webview> fullscreen, e.g.

<webview>.addEventListener('permissionrequest', function(e) {
  if (e.permission === 'fullscreen') e.request.allow();
});

Now perform necessary action to request fullscreen from the <webview>, for the
youtube case, this would be fullscreening the video player.

Check that the element enters fullscreen mode.

Review URL: https://codereview.chromium.org/984963004

Cr-Commit-Position: refs/heads/master@{#321282}

2 files changed, 25 insertions, 0 deletions

diff --git a/extensions/renderer/guest_view/guest_view_internal_custom_bindings.cc b/extensions/renderer/guest_view/guest_view_internal_custom_bindings.cc
index a57f454..8bc2a2e 100644
--- a/extensions/renderer/guest_view/guest_view_internal_custom_bindings.cc
+++ b/extensions/renderer/guest_view/guest_view_internal_custom_bindings.cc
@@ -15,6 +15,7 @@
 #include "extensions/renderer/guest_view/extensions_guest_view_container.h"
 #include "extensions/renderer/script_context.h"
 #include "third_party/WebKit/public/web/WebFrame.h"
+#include "third_party/WebKit/public/web/WebScopedUserGesture.h"
 #include "third_party/WebKit/public/web/WebView.h"
 #include "v8/include/v8.h"
 
@@ -43,6 +44,10 @@ GuestViewInternalCustomBindings::GuestViewInternalCustomBindings(
       base::Bind(
           &GuestViewInternalCustomBindings::RegisterElementResizeCallback,
           base::Unretained(this)));
+  RouteFunction(
+      "RunWithGesture",
+      base::Bind(&GuestViewInternalCustomBindings::RunWithGesture,
+                 base::Unretained(this)));
 }
 
 void GuestViewInternalCustomBindings::AttachGuest(
@@ -198,4 +203,14 @@ void GuestViewInternalCustomBindings::RegisterElementResizeCallback(
   args.GetReturnValue().Set(v8::Boolean::New(context()->isolate(), true));
 }
 
+void GuestViewInternalCustomBindings::RunWithGesture(
+    const v8::FunctionCallbackInfo<v8::Value>& args) {
+  // Gesture is required to request fullscreen.
+  blink::WebScopedUserGesture user_gesture;
+  CHECK_EQ(args.Length(), 1);
+  CHECK(args[0]->IsFunction());
+  v8::Handle<v8::Value> no_args;
+  context()->CallFunction(v8::Handle<v8::Function>::Cast(args[0]), 0, &no_args);
+}
+
 }  // namespace extensions
diff --git a/extensions/renderer/guest_view/guest_view_internal_custom_bindings.h b/extensions/renderer/guest_view/guest_view_internal_custom_bindings.h
index 2c19137..b28634f 100644
--- a/extensions/renderer/guest_view/guest_view_internal_custom_bindings.h
+++ b/extensions/renderer/guest_view/guest_view_internal_custom_bindings.h
@@ -55,6 +55,16 @@ class GuestViewInternalCustomBindings : public ObjectBackedNativeHandler {
   // a single parameter, |callback|.
   void RegisterElementResizeCallback(
       const v8::FunctionCallbackInfo<v8::Value>& args);
+
+  // Runs a JavaScript function with user gesture.
+  //
+  // This is used to request webview element to enter fullscreen (from the
+  // embedder).
+  // Note that the guest requesting fullscreen means it has already been
+  // triggered by a user gesture and we get to this point if embedder allows
+  // the fullscreen request to proceed.
+  void RunWithGesture(
+      const v8::FunctionCallbackInfo<v8::Value>& args);
 };
 
 }  // namespace extensions