Remove ContextClient from NavigatorBeacon

Now that Navigator's Supplements can retrieve the Navigator object with host(),
those Supplements don't need to observe ContextClient.

BUG=610176

Review-Url: https://codereview.chromium.org/2611133002
Cr-Commit-Position: refs/heads/master@{#442873}

third_party/WebKit/Source/modules/beacon/NavigatorBeacon.cpp

@@ -22,12 +22,11 @@
 namespace blink {
 
 NavigatorBeacon::NavigatorBeacon(Navigator& navigator)
-    : ContextClient(navigator.frame()), m_transmittedBytes(0) {}
+    : Supplement<Navigator>(navigator), m_transmittedBytes(0) {}
 
 NavigatorBeacon::~NavigatorBeacon() {}
 
 DEFINE_TRACE(NavigatorBeacon) {
-  ContextClient::trace(visitor);
   Supplement<Navigator>::trace(visitor);
 }
 
@@ -71,15 +70,15 @@ bool NavigatorBeacon::canSendBeacon(ExecutionContext* context,
   }
 
   // If detached from frame, do not allow sending a Beacon.
-  if (!frame() || !frame()->client())
+  if (!host()->frame())
     return false;
 
   return true;
 }
 
 int NavigatorBeacon::maxAllowance() const {
-  DCHECK(frame());
-  const Settings* settings = frame()->settings();
+  DCHECK(host()->frame());
+  const Settings* settings = host()->frame()->settings();
   if (settings) {
     int maxAllowed = settings->getMaxBeaconTransmission();
     if (maxAllowed < m_transmittedBytes)
@@ -100,19 +99,26 @@ bool NavigatorBeacon::sendBeacon(
     const String& urlstring,
     const ArrayBufferViewOrBlobOrStringOrFormData& data,
     ExceptionState& exceptionState) {
-  NavigatorBeacon& impl = NavigatorBeacon::from(navigator);
+  return NavigatorBeacon::from(navigator).sendBeaconImpl(scriptState, urlstring,
+                                                         data, exceptionState);
+}
 
+bool NavigatorBeacon::sendBeaconImpl(
+    ScriptState* scriptState,
+    const String& urlstring,
+    const ArrayBufferViewOrBlobOrStringOrFormData& data,
+    ExceptionState& exceptionState) {
   ExecutionContext* context = scriptState->getExecutionContext();
   KURL url = context->completeURL(urlstring);
-  if (!impl.canSendBeacon(context, url, exceptionState))
+  if (!canSendBeacon(context, url, exceptionState))
     return false;
 
-  int allowance = impl.maxAllowance();
+  int allowance = maxAllowance();
   int bytes = 0;
   bool allowed;
 
   if (data.isArrayBufferView()) {
-    allowed = PingLoader::sendBeacon(impl.frame(), allowance, url,
+    allowed = PingLoader::sendBeacon(host()->frame(), allowance, url,
                                      data.getAsArrayBufferView(), bytes);
   } else if (data.isBlob()) {
     Blob* blob = data.getAsBlob();
@@ -128,20 +134,21 @@ bool NavigatorBeacon::sendBeacon(
         return false;
       }
     }
-    allowed = PingLoader::sendBeacon(impl.frame(), allowance, url, blob, bytes);
+    allowed =
+        PingLoader::sendBeacon(host()->frame(), allowance, url, blob, bytes);
   } else if (data.isString()) {
-    allowed = PingLoader::sendBeacon(impl.frame(), allowance, url,
+    allowed = PingLoader::sendBeacon(host()->frame(), allowance, url,
                                      data.getAsString(), bytes);
   } else if (data.isFormData()) {
-    allowed = PingLoader::sendBeacon(impl.frame(), allowance, url,
+    allowed = PingLoader::sendBeacon(host()->frame(), allowance, url,
                                      data.getAsFormData(), bytes);
   } else {
-    allowed =
-        PingLoader::sendBeacon(impl.frame(), allowance, url, String(), bytes);
+    allowed = PingLoader::sendBeacon(host()->frame(), allowance, url, String(),
+                                     bytes);
   }
 
   if (allowed) {
-    impl.addTransmittedBytes(bytes);
+    addTransmittedBytes(bytes);
     return true;
   }
 

third_party/WebKit/Source/modules/beacon/NavigatorBeacon.h

@@ -5,7 +5,6 @@
 #ifndef NavigatorBeacon_h
 #define NavigatorBeacon_h
 
-#include "core/dom/ContextLifecycleObserver.h"
 #include "core/frame/Navigator.h"
 #include "platform/Supplementable.h"
 #include "platform/heap/Handle.h"
@@ -18,7 +17,6 @@ class KURL;
 class ArrayBufferViewOrBlobOrStringOrFormData;
 
 class NavigatorBeacon final : public GarbageCollectedFinalized<NavigatorBeacon>,
-                              public ContextClient,
                               public Supplement<Navigator> {
   USING_GARBAGE_COLLECTED_MIXIN(NavigatorBeacon);
 
@@ -39,6 +37,10 @@ class NavigatorBeacon final : public GarbageCollectedFinalized<NavigatorBeacon>,
 
   static const char* supplementName();
 
+  bool sendBeaconImpl(ScriptState*,
+                      const String&,
+                      const ArrayBufferViewOrBlobOrStringOrFormData&,
+                      ExceptionState&);
   bool canSendBeacon(ExecutionContext*, const KURL&, ExceptionState&);
   int maxAllowance() const;
   void addTransmittedBytes(int sentBytes);

third_party/WebKit/Source/platform/Supplementable.h

@@ -98,7 +98,12 @@ class Supplement : public GarbageCollectedMixin {
   // TODO(haraken): Remove the default constructor.
   // All Supplement objects should be instantiated with m_host.
   Supplement() {}
+
   explicit Supplement(T& host) : m_host(&host) {}
+
+  // Supplementable and its supplements live and die together.
+  // Thus host() should never return null (if the default constructor
+  // is completely removed).
   T* host() const { return m_host; }
 
   static void provideTo(Supplementable<T>& host,