Have AudioContextManagerImpl derive from content::FrameServiceBase.

This is a fix suggested by dcheng@ at:
https://bugs.chromium.org/p/chromium/issues/detail?id=888366#c12

Locally confirmed the change stops the crash.

Bug: 888366
Test: The CL build does not crash on the repro case anymore.
Change-Id: I4b56228589b4c71f1191fb82e849240f39c938ed
Reviewed-on: https://chromium-review.googlesource.com/1246945
Commit-Queue: Hongchan Choi <hongchan@chromium.org>
Reviewed-by: Olga Sharonova <olka@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Raymond Toy <rtoy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595127}

content/browser/media/webaudio/OWNERS

+hongchan@chromium.org
+rtoy@chromium.org
+
+# COMPONENT: Blink>WebAudio
\ No newline at end of file

content/browser/media/webaudio/audio_context_manager_impl.cc

@@ -15,14 +15,18 @@ namespace content {
 void AudioContextManagerImpl::Create(
     RenderFrameHost* render_frame_host,
     blink::mojom::AudioContextManagerRequest request) {
-  mojo::MakeStrongBinding(
-      std::make_unique<AudioContextManagerImpl>(render_frame_host),
-      std::move(request));
+  DCHECK(render_frame_host);
+
+  // The object is bound to the lifetime of |render_frame_host| and the mojo
+  // connection. See FrameServiceBase for details.
+  new AudioContextManagerImpl(render_frame_host, std::move(request));
 }
 
 AudioContextManagerImpl::AudioContextManagerImpl(
-    RenderFrameHost* render_frame_host)
-    : render_frame_host_impl_(
+    RenderFrameHost* render_frame_host,
+    blink::mojom::AudioContextManagerRequest request)
+    : FrameServiceBase(render_frame_host, std::move(request)),
+      render_frame_host_impl_(
           static_cast<RenderFrameHostImpl*>(render_frame_host)) {
   DCHECK(render_frame_host);
 }

content/browser/media/webaudio/audio_context_manager_impl.h

@@ -6,6 +6,7 @@
 #define CONTENT_BROWSER_MEDIA_WEBAUDIO_AUDIO_CONTEXT_MANAGER_IMPL_H_
 
 #include "content/common/content_export.h"
+#include "content/public/browser/frame_service_base.h"
 #include "mojo/public/cpp/bindings/binding.h"
 #include "third_party/blink/public/mojom/webaudio/audio_context_manager.mojom.h"
 
@@ -17,10 +18,12 @@ class RenderFrameHostImpl;
 // Implements the mojo interface between WebAudio and the browser so that
 // WebAudio can report when audible sounds from an AudioContext starts and
 // stops.
-class CONTENT_EXPORT AudioContextManagerImpl
-    : public blink::mojom::AudioContextManager {
+class CONTENT_EXPORT AudioContextManagerImpl final
+    : public content::FrameServiceBase<blink::mojom::AudioContextManager> {
  public:
-  explicit AudioContextManagerImpl(RenderFrameHost* render_frame_host);
+  explicit AudioContextManagerImpl(
+      RenderFrameHost* render_frame_host,
+      blink::mojom::AudioContextManagerRequest request);
   ~AudioContextManagerImpl() override;
 
   static void Create(RenderFrameHost* render_frame_host,