Add MemoryBlockRetrievalFailed() hook.

Adjust RetrieveMemoryBlockJob to call said hook if we fail to fulfill
the memory read request.

src/apps/debugger/jobs/RetrieveMemoryBlockJob.cpp

@@ -46,15 +46,19 @@ RetrieveMemoryBlockJob::Do()
 {
 	ssize_t result = fTeamMemory->ReadMemory(fMemoryBlock->BaseAddress(),
 		fMemoryBlock->Data(), fMemoryBlock->Size());
-	if (result < 0)
+	if (result < 0) {
+		fMemoryBlock->NotifyDataRetrieved(result);
 		return result;
+	}
 
 	uint32 protection = 0;
 	uint32 locking = 0;
 	status_t error = get_memory_properties(fTeam->ID(),
 		(const void *)fMemoryBlock->BaseAddress(), &protection, &locking);
-	if (error != B_OK)
+	if (error != B_OK) {
+		fMemoryBlock->NotifyDataRetrieved(error);
 		return error;
+	}
 
 	fMemoryBlock->SetWritable((protection & B_WRITE_AREA) != 0);
 	fMemoryBlock->MarkValid();

src/apps/debugger/model/TeamMemoryBlock.cpp

@@ -93,11 +93,14 @@ TeamMemoryBlock::SetWritable(bool writable)
 
 
 void
-TeamMemoryBlock::NotifyDataRetrieved()
+TeamMemoryBlock::NotifyDataRetrieved(status_t result)
 {
 	for (ListenerList::Iterator it = fListeners.GetIterator();
 			Listener* listener = it.Next();) {
-		listener->MemoryBlockRetrieved(this);
+		if (result == B_OK)
+			listener->MemoryBlockRetrieved(this);
+		else
+			listener->MemoryBlockRetrievalFailed(this, result);
 	}
 }
 
@@ -123,3 +126,10 @@ void
 TeamMemoryBlock::Listener::MemoryBlockRetrieved(TeamMemoryBlock* block)
 {
 }
+
+
+void
+TeamMemoryBlock::Listener::MemoryBlockRetrievalFailed(TeamMemoryBlock* block,
+	status_t result)
+{
+}

src/apps/debugger/model/TeamMemoryBlock.h

@@ -44,7 +44,7 @@ public:
 			bool			IsWritable() const		{ return fWritable; }
 			void			SetWritable(bool writable);
 
-			void			NotifyDataRetrieved();
+			void			NotifyDataRetrieved(status_t result = B_OK);
 
 protected:
 	virtual void			LastReferenceReleased();
@@ -69,6 +69,9 @@ public:
 	virtual					~Listener();
 
 	virtual void			MemoryBlockRetrieved(TeamMemoryBlock* block);
+
+	virtual	void			MemoryBlockRetrievalFailed(TeamMemoryBlock* block,
+								status_t result);
 };